The effectiveness of criminal investigation methods in apprehending perpetrators and enhancing the probative force of evidence

DOI:https://doi-0004.org/6812/17912963458844

Nadjib Beroual

University of Batna1, Algeria.

Email: drnadjibberoual@gmail.com

Received: 22/04/2026 ;                Accepted: 25/09/2026;                    Published: 07/10/2026

Abstract

This study aims to analyze the effectiveness of criminal investigation methods in apprehending perpetrators and enhancing the probative force of evidence in Algerian legislation, in light of the developments enacted by Law No. 25-14 dated August 3, 2025, containing the Code of Criminal Procedure. The importance of the subject stems from the development that crime has undergone, particularly organized and modern crimes, which rendered traditional means of search insufficient on their own to uncover criminal activity and reach its perpetrators. The Algerian legislator has adopted a set of special investigation methods, including the interception of correspondence, recording of sounds, capturing of images, and infiltration, and subjected them to legal and judicial controls aimed at achieving a balance between the requirements of effective crime control and respect for procedural legality and rights and freedoms. The study focuses particularly on infiltration as one of the investigation methods most closely associated with concealment, the use of a assumed identity, and deception, while examining the boundaries separating legitimate procedural deception and unlawful incitement to commit a crime. The study also addresses the evidentiary value of outcomes obtained from investigation methods, in light of the principle of freedom of proof, judicial conviction, the conditions for the validity of reports and evidence, and the legality of the procedures for obtaining them. The study concludes that the effectiveness of investigation methods is not measured merely by their ability to reach perpetrators, but rather is reinforced by the extent of their respect for legal controls that accord the evidence obtained from them judicial admissibility.

Keywords: Criminal investigation methods; Infiltration; Procedural deception; Apprehending perpetrators; Criminal proof; Probative force of evidence; Law No. 25-14.

Introduction

The rapid evolution in the forms of crime and the means of committing it has spawned more organized and complex criminal patterns, which traditional search and investigation means are no longer capable, in all cases, of uncovering with the necessary speed and effectiveness—particularly in the realm of organized and transboundary crime, drug offenses, money laundering, corruption, terrorism, and crimes related to information and communication technologies. This transformation has imposed on criminal legislation the need to keep pace with the nature of contemporary criminality by developing search and investigation tools, thereby enhancing the capacity of criminal justice authorities to access information related to crime, expose its perpetrators, and gather the evidence necessary to prove it.

In this context, the Algerian legislator has gradually moved toward adopting a set of special investigation methods that allow for confronting crimes characterized by their covert or organized nature, while surrounding their use with legal controls that ensure a balance between the requirements of combating crime and the imperatives of protecting rights and freedoms. This orientation reflects an awareness of the importance of developing search and investigation tools in line with the transformations experienced by the criminal phenomenon, while keeping the use of these means within the framework defined by procedural legality. Algerian jurisprudence has pointed out that recourse to these methods was fundamentally linked to the need to overcome the difficulties posed by contemporary crimes to traditional means of searching for evidence, while subjecting them to specific legal conditions and guarantees (Rouis, 2017, pp. 38–50).

This direction was further reinforced by the enactment of Law No. 25-14 dated August 3, 2025, containing the Code of Criminal Procedure, which reorganized the procedural framework within a legislative context responsive to the demands of contemporary criminal justice, while affirming a number of fundamental principles governing criminal proceedings—chief among them legality, a fair trial, respect for human dignity and rights, the presumption of innocence, and the interpretation of doubt in favor of the accused, in addition to the requirement to state the reasons for judicial judgments, decisions, and orders (Law No. 25-14, 2025, Article 1).

Special investigation methods acquire increasing importance in this framework given the nature of the procedures upon which they rely; some may take place without the knowledge of the individuals under investigation, thus allowing access to information and evidence that are difficult to obtain through traditional means. On the other hand, the specific nature of these methods requires surrounding them with clear legal controls to ensure that the requirements of effective crime detection do not turn into an unjustified infringement upon private life or individual freedoms. Therefore, the effectiveness of investigation methods is not measured merely by their ability to reach suspects, but extends to the propriety of the procedures followed and the capacity of the results obtained from them to be relied upon in the judicial sphere.

Infiltration emerges in this context as one of the investigation methods most closely connected to the concept of concealment and procedural deception, given that the practitioner penetrates the criminal milieu and misleads the persons under investigation into believing that he is an perpetrator, an accomplice, or an accessory with them, with the intention of gathering information and uncovering criminal activity and its perpetrators. Algerian jurisprudence has addressed infiltration as a means of searching for criminal evidence in the face of certain forms of serious and complex crimes, given its ability to reach data that is difficult to uncover through traditional means (Zouzou, 2014, pp. 115–124; Ghezioui and Lasseldj, 2021, pp. 145–159).

Law No. 25-14 devoted special attention to this method, regulating it within Articles 120 to 127, defining the conditions for its practice, the authority authorized to permit it, its duration, and the mechanisms for protecting the identity of the practitioner, while permitting—within the limits of the operation—certain acts necessitated by the nature of infiltration. In contrast, the legislator set a fundamental limit that may not be crossed, consisting of the inadmissibility of the operation constituting incitement to commit crimes, and provided that violation of this restriction entails nullity (Law No. 25-14, 2025, Articles 120–127). This provision holds particular importance in drawing the boundary line separating legitimate procedural deception—which aims to uncover an existing criminal activity—and incitement to crime, which would shift the investigator’s role from merely uncovering the crime to contributing to its genesis or pushing the person to commit it.

The effectiveness of investigation methods is inseparable from the question of the probative force of the evidence obtained from them, as the purpose of search and investigation procedures is not limited to uncovering the crime and apprehending its perpetrators, but extends to producing evidence that can be presented before the judiciary and evaluated in accordance with the established rules in the field of criminal proof. Therefore, the propriety of the procedure through which the evidence was obtained, compliance with the conditions and limits drawn by the law, and the proper documentation of the results obtained from it represent essential elements in determining the extent to which they can be judicially recognized. Algerian legal writings have emphasized the importance of linking the legality of evidence to procedural legality, considering that violating the rules governing the collection of evidence may affect its legal value and the possibility of relying upon it before the courts (Ayyadi and Khadiji, 2024, pp. 129–139).

Accordingly, the relationship between the effectiveness of investigation methods and the probative force of evidence requires examining the subject from two complementary angles: the first consists of the extent of these methods’ ability to uncover criminal activity and reach its perpetrators, while the second relates to the propriety of the results obtained from them and their capacity for judicial reliance. The success of a particular investigation method in reaching the perpetrator does not achieve the complete legal purpose if the conditions for its use were not met or if the resulting evidence was flawed by what affects its legality; likewise, compliance with legal controls should not be understood as an obstacle to the effectiveness of search and investigation bodies, but rather as a supporting element for the integrity of their results and their strength before the judiciary.

From this standpoint, the study’s main problem is defined in the following question:

To what extent have the criminal investigation methods enshrined in Criminal Procedure Law No. 25-14 contributed to enhancing the effectiveness of crime detection and apprehending perpetrators, and to what extent does the legality of these methods—particularly infiltration—reflect on the probative force of the evidence obtained from them before the judiciary?

From this main problem, the following two questions branch out:

• What is the extent of the effectiveness of special investigation methods in uncovering crimes and apprehending their perpetrators?
• What are the limits of the probative force of evidence obtained from these methods in light of the controls of legality and criminal proof?

The study proceeds from a basic hypothesis stating that the effectiveness of special investigation methods does not fundamentally conflict with the requirements of procedural legality, but rather its practical and evidentiary value is reinforced whenever it is used in accordance with the conditions and controls specified by law, particularly regarding infiltration and the distinction between procedural deception aimed at uncovering existing criminal activity, and incitement that leads to creating the crime or pushing a person to commit it.

To address the posed problem, the study adopts the analytical method through analyzing the legal texts governing special investigation methods and the rules of proof in Law No. 25-14, drawing upon jurisprudence and relevant legal studies to interpret the legal provisions and clarify their effects. The comparative method is also employed to a limited extent when necessary, especially regarding the dividing line between legitimate investigation methods and incitement to commit a crime.

The study is divided into two main sections: the first deals with the effectiveness of criminal investigation methods in uncovering crime and apprehending perpetrators, while the second is devoted to examining the probative force of evidence obtained from investigation methods and the controls for its judicial admissibility.

1. The Effectiveness of Criminal Investigation Methods in Uncovering Crime and Apprehending Perpetrators

Crime in its contemporary form has witnessed remarkable development in terms of the methods of its commission, its organization, and the means used to execute it and conceal its traces. In many of its forms, it is no longer based on overt individual activity that can be uncovered by traditional means of search and investigation; rather, it has taken on, in numerous cases, an organized character based on secrecy, planning, division of roles, and benefiting from technological development and modern means of communication. This transformation has led to the emergence of practical difficulties for search and investigation bodies, making reliance on traditional means alone insufficient in confronting certain forms of complex criminality—particularly organized crime, cybercrime, drug offenses, terrorism, corruption, and other crimes characterized by a high degree of concealment and caution in their execution (Rouis, 2017, pp. 38–50).

Proceeding from this, the Algerian legislator has moved toward adopting a set of special investigation methods that allow judicial police bodies to access information and evidence that may be impossible to obtain through traditional procedures. Law No. 25-14, containing the Code of Criminal Procedure, enshrined this approach by regulating a number of these methods—including the interception of correspondence, recording of sounds, and capturing of images, alongside infiltration—while subjecting them to a set of legal conditions and controls.

The legislative recognition of these means does not imply granting absolute authority to investigation bodies in using them; rather, it means subjecting them to a special procedural regime that specifies the crimes for which recourse to them is permitted, the competent authority to issue authorization, execution conditions, duration, and the manner in which operations and obtained results are documented. This reflects a legislative direction based on balancing the requirements of combating crime on one hand, and respecting procedural legality, rights, and freedoms on the other.

This is evident through Articles 114 to 119 of Law No. 25-14, which regulated the interception of correspondence, recording of sounds, and capturing of images, linking recourse to them to the necessities of inquiry or investigation and regarding crimes specified by law, while subjecting them to authorization and supervision in accordance with legally prescribed conditions and procedures (Law No. 25-14, 2025, Articles 114–119).

The importance of these controls emerges given the special nature of these procedures, as their use may entail infringement upon certain aspects of private life or secrecy surrounding individuals’ relationships and communications. Therefore, the legality of their use is derived not only from their practical necessity in combating crime, but also from the existence of a legal basis defining their scope, objectives, duration, and the entity competent to practice them. On this basis, the effectiveness of investigation methods is not measured merely by their ability to reach information, but should rather be viewed as a legal and evidentiary effectiveness—that is, the capacity of the method to uncover crime in a lawful manner and produce elements that can be relied upon before the judiciary.

From this perspective, special investigation methods do not represent a departure from the rules of procedural legality, but are rather among the means made available by law to confront an evolving criminal nature, provided they are exercised within the boundaries drawn by the legislator. Their real effectiveness is achieved when three interconnected elements are present: the suitability of the method to the nature of the crime, the legality of its use, and its capacity to produce evidence of value in criminal proceedings.

1.1. Infiltration as an Effective Method for Uncovering Criminal Activity

Infiltration is distinguished from other special investigation methods by its interactive nature, as it is not limited to monitoring criminal activity from the outside, but relies on the infiltrator’s integration into the environment in which the acts under investigation take place, allowing him direct access to information, relationships, and roles that are difficult to uncover through external surveillance means.

Infiltration, in its essence, is based on a judicial police officer or agent—under the responsibility of the judicial police officer tasked with coordinating the operation—surveilling persons suspected of committing a felony or misdemeanor, by misleading them into believing that he is an perpetrator with them, an accomplice, or an accessory, thereby allowing him to approach the criminal activity and monitor it from within (Zouzou, 2014, pp. 115–124).

The practical value of this method is manifested in its ability to overcome the barriers imposed by the secrecy surrounding criminal groups, as knowing the identities of their members, their roles, their communication methods, their funding sources, or the means they rely on in executing their activity may not be possible through traditional surveillance alone. Therefore, infiltration—when conducted within a legal framework—allows for obtaining direct information that assists in identifying elements of the criminal network and uncovering the nature of the activity it practices, thereby contributing to apprehending its perpetrators and presenting them to judicial authorities (Wada’i, 2018, pp. 200–217).

Law No. 25-14 devoted Articles 120 to 127 to regulating the infiltration process, surrounding it with a set of substantive and formal conditions relating to the nature of the operation, the entity undertaking its execution, its authorization, its duration, and the acts permitted to be performed within its framework, in addition to establishing special protection for the infiltrator’s identity (Law No. 25-14, 2025, Articles 120–127).

Determining these conditions holds special importance because the nature of infiltration requires granting the infiltrator a degree of flexibility in dealing with the criminal environment; however, this flexibility cannot turn into an unlimited authority to commit acts or exceed the purpose for which the procedure was authorized. For this reason, the legislator surrounded the operation with restrictions ensuring that the infiltrator’s activity remains linked to the original purpose of the investigation—namely, uncovering an existing crime, apprehending its perpetrators, and gathering evidence regarding it.

Hence, the effectiveness of infiltration is not linked solely to its ability to reach the heart of the criminal activity, but also to its ability to achieve this goal without violating the legal boundaries governing the operation. Whenever it is possible to combine the informational depth provided by infiltration with procedural discipline ensuring its legality, its value increases as a means of search and investigation and as a means of producing evidence that can be introduced and debated before the judiciary.

1.2. Procedural Deception Between Uncovering Crime and Incitement to Commit It

Deception acquires special importance within the framework of infiltration, given that the success of the operation relies in part on misleading the persons under investigation regarding the actual reality of the infiltrator’s identity or capacity, allowing him to build an apparent relationship with them that enables access to information linked to the criminal activity. From this angle, deception does not represent an independent end in itself, but is rather considered a procedural means deriving its legality from the purpose for which it is used and from the boundaries set by law for its exercise.

However, the use of deception in the field of investigation raises a delicate issue consisting of the necessity to distinguish between uncovering existing criminal activity and creating criminal activity or pushing a person to commit a crime they were not prepared to commit. The authority charged with investigation may conceal itself to reach an already existing criminal activity and uncover its elements, tools, and persons, but it does not possess, under the cover of investigation, the right to create criminal intent or push a person to commit an act they would not have proceeded with but for its intervention.

The Algerian legislator explicitly settled this issue in Article 121 of Law No. 25-14, when it permitted the infiltrator to surveil persons suspected of committing crimes by misleading them into believing he is an perpetrator, accomplice, or accessory, while simultaneously prohibiting him from performing acts that constitute incitement to commit crimes, and provided that violation of this restriction entails nullity (Law No. 25-14, 2025, Article 121).

The legal importance of this provision lies in setting a dividing boundary between legitimate deception as a means of uncovering crime and unlawful incitement as a means of creating it. Legitimate procedural deception aims to uncover an existing criminal reality, whereas incitement leads to shifting the authority’s position from a mere discoverer of the crime to an influential party in its genesis. A fundamental difference in evaluating the evidence obtained from the operation results from this distinction; for it is not sufficient that the evidence contributed to apprehending a person or uncovering an event, but it is also necessary to verify the manner in which it was reached and the extent of compliance with the legal rules governing the operation.

Accordingly, the criterion of legality should not be limited to the question of whether the infiltration operation yielded a successful result from a security standpoint, but extends to examining the nature of the role played by the infiltrator in forming the criminal event. If his role was limited to uncovering an already existing activity, monitoring it, and documenting its elements, that falls within the scope of the original function of investigation. However, if his intervention exceeded the boundaries of detection and monitoring to exert a decisive influence on the person’s will and push them to commit the crime, the matter raises an issue regarding the legality of the procedure and the propriety of the resulting evidence.

The close relationship between investigation effectiveness and the probative force of evidence becomes clear here; the operation’s success in apprehending the perpetrator does not alone represent a sufficient criterion to judge its effectiveness from a legal standpoint. A method may achieve a direct field result, but if reached through a procedure violating legal controls, the evidentiary value of the results obtained from it becomes questionable. Conversely, an investigation that uncovers an existing criminal activity and takes place within the framework of authorization, conditions, and boundaries established by law is more capable of producing evidence possessing procedural integrity and judicial defensibility.

Thus, it becomes clear that the desired effectiveness of special investigation methods does not consist of merely reaching the perpetrator, but in achieving an integrated equation based on uncovering the crime, apprehending its perpetrators, and simultaneously preserving the legality of the method and the integrity of the evidence. The more a procedure respects legal controls, the more capable the results obtained from it are of standing up to judicial review, which makes procedural legality a complementary element to investigation effectiveness rather than a separate constraint upon it.

On this basis, it can be said that the Algerian legislator did not view the effectiveness of investigation methods as an antithesis to procedural legality, but sought to frame them legally in a way that allows search and investigation bodies to confront complex and covert forms of criminality, while keeping the exercise of these means within boundaries that ensure the legality of evidence and respect for fundamental guarantees of individuals. Hence, the true effectiveness of an investigation method is measured by its capacity to combine efficiency in uncovering crime with efficiency in producing legal evidence admissible before the judiciary.

 2. The Probative Force of Evidence Obtained from Investigation Methods and Controls for Its Judicial Admissibility

If special investigation methods were created to confront the difficulties posed by complex and covert crimes, their effectiveness is not completed merely by enabling search and investigation bodies to access information or apprehend suspects, but extends to the extent to which the results obtained from them are fit to enter the evidentiary process and be relied upon before the judiciary. Information reached during an investigation does not acquire, merely by virtue of being obtained, the value of evidence capable of judicial recognition; rather, this depends on the extent to which the legal rules governing its collection, documentation, presentation, and debate are respected.

Hence, examining the probative force of evidence obtained from investigation methods requires distinguishing between three interrelated yet distinct issues: the legality of the method by which the evidence was obtained, the procedural propriety of the evidence, and the value assigned to it by the judge within the framework of judicial conviction. This distinction acquires special importance in the field of special investigation, given the exceptional nature of some of its procedures and what they may entail by way of interference in private life or the use of means of concealment and deception.

2.1. The Legality of Evidence Obtained from Investigation Methods

The legal value of evidence cannot be determined in isolation from the manner in which it was obtained; criminal evidence does not represent mere information that can be used to prove an accusation, but is rather the result of a procedural process presumed to take place according to the rules defined by law. Therefore, the propriety of evidence is linked, first and foremost, to the legality of the method that led to obtaining it.

Law No. 25-14 enshrines this concept by combining the general principles governing criminal proceedings with the specific provisions regulating search and investigation tools. Article 1 thereof provides for a set of fundamental principles—among them legality, the presumption of innocence, fair trial guarantees, and respect for human rights—which frame the exercise of search and investigation powers and are inseparable from the detailed rules governing evidence collection procedures (Law No. 25-14, 2025, Article 1).

Thus, procedural legality does not represent an obstacle to combating crime, but constitutes the legal framework that grants investigation procedures their legality and ensures the integrity of their outcomes. Whenever the method used is grounded in a legal text, executed by the competent authority, and within the limits drawn by law, the results obtained from it can be viewed as part of the evidentiary process. However, if the procedure exceeds its established limits, the mere importance of the reached result is not, in itself, sufficient to confer legality upon it.

This rule is reaffirmed particularly in the field of special investigation methods because the legislator did not merely permit them, but surrounded their use with a set of conditions and restrictions defining their scope. This appears, for example, in requiring authorization for certain procedures, specifying the crimes for which recourse to them is permissible, fixing their duration, and determining the executing entity, as well as the necessity to adhere to the content of the authorization without exceeding it.

In this context, the most important prerequisites for the legality of evidence obtained from investigation methods can be identified in a set of core controls, consisting of:

1. Existence of a legal basis for the procedure: The investigation method used must be established by a clear legal text, preventing individuals from being subjected to procedures affecting their rights and freedoms without legislative backing. The legality of the end alone is insufficient to justify the means; the means itself must be grounded in a legal basis.
2. Issuance of authorization by the competent authority: Whenever the law requires prior authorization, respecting jurisdiction in its issuance constitutes an essential element in the procedure’s propriety. This is not a mere formal requirement, but a guarantee aimed at subjecting recourse to special means to the supervision of an authority possessing legal jurisdiction.
3. Connection of the procedure to a crime for which the law permits using the method: The legislator did not make special investigation methods general tools to be used across all crimes indiscriminately, but linked some of them to a specific nature of crimes, given their severity or the specific nature of the means of their commission. Therefore, the use of the method must be connected to the incident regarding which the authorization was issued.
4. Compliance with the statutory duration: Duration is an element of procedural legality, as continuing the procedure after the expiration of the legally specified period or without renewal according to prescribed conditions prevents leaving the procedural intervention open indefinitely.
5. Adherence to the limits and content of the authorization: The issuance of the authorization in itself is not sufficient; the operation must be executed within its scope and for the purpose for which it was issued. Therefore, expanding execution beyond legally established limits may affect the propriety of the results obtained from it.
6. Documentation of the operation and its results according to legal forms: The documentation process acquires special importance regarding evidence obtained from special investigation means, as it allows proving the circumstances of collecting the evidence, its source, and how it was obtained, enabling the judiciary and the defense to verify the propriety of the procedure.
7. Non-transformation of the investigation into incitement to commit the crime: This condition holds special importance in the infiltration process; the legislator permitted the infiltrator to use deception and an assumed identity to monitor criminal activity, but prohibited him from incitement to commit crimes and attached nullity to its violation (Law No. 25-14, 2025, Article 121). This provision reflects the legislator’s keenness to keep the authority’s role within the scope of uncovering an existing crime, without shifting to influencing criminal intent or creating crime out of nothing.

These controls intersect with the conclusions of Ayyadi and Khadiji that the legality of procedures for obtaining evidence represents a fundamental guarantee for protecting rights and freedoms, and that violating the rules governing evidence collection can affect its legal value and the extent of its judicial admissibility (Ayyadi and Khadiji, 2024, pp. 129–139).

Accordingly, the legality of evidence obtained from investigation methods should not be understood as an automatic result of mere legal recognition of the method, but as a result of the compliance of the method, procedure, execution, and outcome with the legal rules governing them. A legal method does not necessarily produce evidence binding on the judge, but it provides the first condition for such evidence to enter the domain of judicial evaluation.

2.2. Probative Force of Evidence and Judicial Conviction

While the legality of the method represents the main gateway to the evidentiary process, it does not mean that the resulting evidence enjoys absolute probative force or binding evidentiary weight upon the judge. The criminal justice system is based on distinguishing between the admissibility of evidence for consideration and the value assigned to it by the judge after evaluation.

Law No. 25-14 enshrined this approach through Article 349, which establishes that crimes may be proven by all methods of proof, including electronic evidence, unless the law provides otherwise, and further establishes that the judge decides according to his personal conviction and builds his judgment only on evidence presented before him and debated during the hearing (Law No. 25-14, 2025, Article 349).

Consequently, evidence resulting from a lawful investigation method does not impose itself on the judge merely due to the legality of its source; legality renders it fit to enter the evidentiary process, while assessing its weight and persuasiveness remains subject to the judge’s discretionary authority within the framework of judicial conviction. Evidence may be procedurally legal yet of limited value when compared to the remaining elements of the case, or it may acquire greater weight when aligned with other corroborating evidence and presumptions.

This issue emerges particularly regarding reports and statements drafted by the judicial police on the occasion of executing investigation methods. Law No. 25-14 established rules regarding the validity of reports, the conditions for drafting them, and the data to be included therein, and established—regarding judicial police reports and statements in felonies and misdemeanors—that they fundamentally constitute mere investigative information, unless the law provides otherwise (Law No. 25-14, 2025, Articles 351–352).

This framework reveals that the legislator distinguishes between the existence of evidence in the case file and the probative force that may be granted to it by the judge. Including a report, recording, image, or other results obtained from an investigation within the case file does not necessarily mean that it has settled the dispute regarding criminal liability; rather, it remains subject to presentation, debate, and evaluation according to established rules in criminal proof.

The importance of this distinction increases regarding special investigation methods, as the nature of these methods may lead to producing diverse evidentiary materials, such as recordings, images, and information obtained during an infiltration process or through other means. Hence, it is necessary to verify not only the existence of this material, but also its source, the circumstances of obtaining it, the extent of compliance with legal procedures, the propriety of its documentation, and the possibility of debating it before the judiciary.

Accordingly, probative force in this field should not be reduced to the concept of binding force; rather, judicial admissibility of evidence is understood as the outcome of an integrated pathway starting from the legality of the method, passing through the proper collection and documentation of evidence, and ending with evaluating its value in light of the totality of the case elements.

It follows that a defect in one of the preceding links can affect the final outcome. If the investigation method is illegal, or if the conditions of the authorization were exceeded, or if incitement to commit the crime occurred where prohibited by law, the integrity of the resulting evidence becomes questionable. Conversely, if the legal rules governing the operation are respected, the evidence enters the realm of evidence that the judge may evaluate, without implying a requirement to adopt it or granting it a predetermined value exceeding what he deduces from the elements of the case.

Hence, the relationship between investigation methods and the probative force of evidence is based on a functional complementarity among investigation effectiveness, procedural legality, and judicial conviction. A successful investigation method is not only one that enables reaching the perpetrator or uncovering criminal activity, but also one that produces evidence of sound origin, lawfully obtained, and capable of debate and evaluation before the judiciary. Thus, probative force becomes a natural extension of procedural propriety, rather than an outcome independent from it.

Based on the foregoing, it can be said that Law No. 25-14 struck a balance between the requirements of effective crime detection and the necessity of preserving procedural guarantees; it granted investigation bodies tools proportionate to the evolution of crime, while simultaneously subjecting their use to legal controls and linking the value of the outcomes obtained from them to the general rules of proof and judicial conviction. This confirms that the effectiveness of evidence is measured not only by its ability to prove a fact, but also by the propriety of the path through which it was reached and its ability to withstand judicial review.

3. Evaluation of the Effectiveness of Investigation Methods in Light of Law No. 25-14

Evaluating the effectiveness of special investigation methods requires moving from merely setting forth their legality and conditions of use to assessing their actual capacity to achieve the purpose for which they were created—consisting primarily of uncovering crimes, reaching their perpetrators, and gathering the evidence necessary to attribute criminal liability to them. However, the effectiveness of these tools cannot be measured by a purely security standard, because criminal procedure operates within an integrated legal system that makes protecting society from crime intertwined with respecting procedural legality and fair trial guarantees.

Accordingly, evaluating investigation methods under Law No. 25-14 requires examining them from two complementary angles: the first relates to their practical capacity to confront complex and covert crimes, and the second relates to their capacity to produce legally and evidentiary sound results, allowing them to be relied upon before the judiciary.

3.1. Aspects of Enhancing the Effectiveness of Special Investigation Methods

The aspects of enhancing the effectiveness of special investigation methods in Law No. 25-14 are manifested in a set of elements that allow for developing crime detection tools and adapting them to the nature of contemporary criminal activity.

3.1.1. Diversity and Complementarity of Investigation Methods Searching for crime no longer relies exclusively on traditional tools based on inspection, hearing individuals, and direct information gathering; rather, search and investigation bodies can now, in cases permitted by law, utilize more specialized means, including the interception of correspondence, recording of sounds, capturing of images, and infiltration. This diversity grants investigation bodies a greater capacity to choose the method proportionate to the nature of the crime and its mode of commission, rather than relying on a single method in confronting different criminal patterns (Law No. 25-14, 2025, Articles 114–127).

The importance of this diversity lies not in the multiplicity of means per se, but in the possibility of employing them in an integrated manner to uncover criminal activity and prove its elements. Some crimes can be uncovered through surveillance or recording, whereas crimes based on a secret organization or a closed network require using means that allow access to information from within the criminal environment.

3.1.2. Capacity to Penetrate the Covert Structure of Criminal Activity Infiltration represents one of the most prominent tools that allow overcoming the barriers imposed by criminal secrecy, as it enables the infiltrator to integrate into the targeted environment and monitor the activity of persons under investigation from within. The importance of this appears particularly when accessing information is impossible through external means, owing to the nature of the criminal organization or its members’ reliance on secrecy and caution in their dealings.

From this angle, infiltration provides an added value not available to the same extent in certain other investigation methods, because it allows approaching the source of criminal activity and identifying participating individuals and the roles they perform, alongside the possibility of documenting facts related to the operation. However, this effectiveness remains contingent upon respecting the boundaries drawn by law for infiltration, so that the capacity to integrate into the criminal environment does not turn into unlawful interference in creating the crime.

3.1.3. Enhancing the Capacity to Obtain Documentable Evidence Special investigation methods contribute to moving from mere preliminary information gathering to obtaining, in cases permitted by law, materials that can constitute evidentiary elements—such as recordings, images, correspondence, and other media that can be presented to the judiciary and debated within the framework of criminal proceedings.

This aspect increases in importance given that Law No. 25-14 established the principle of freedom of proof in Article 349 and introduced electronic evidence among the methods of proof that may be relied upon unless a contrary legal provision exists, while keeping its evaluation subject to the judge’s conviction and to what is presented and debated before him (Law No. 25-14, 2025, Article 349). Hence, the evolution in investigation methods is accompanied by an evolution in the nature of materials that can enter the evidentiary process.

3.1.4. Surrounding Investigation Procedures with Legal Controls That Enhance the Integrity of Their Outcomes The effectiveness of a tool is measured not only by its capacity to obtain information, but also by the propriety of the manner in which it was obtained. Therefore, requiring authorization, determining the competent authority, fixing duration, defining the operation’s scope, and documenting its results represent elements contributing to enhancing the legal value of what is obtained.

The importance of these controls lies in providing a degree of supervision over the exercise of special means and limiting the possibility of using them outside the purpose for which they were authorized. They also allow subjecting the results obtained from them to judicial evaluation on the basis of the circumstances of obtaining them and the extent of compliance with the legal procedures governing them.

3.1.5. Providing Legal Protection for Those Executing Certain Investigation Methods Protecting those in charge of investigation operations—particularly protecting the identity of the infiltrator—represents an important element in the effectiveness of these tools, because the nature of undercover work may expose the practitioner to serious risks if his capacity or identity is revealed. Law No. 25-14 attached special importance to this issue by protecting the identity of the infiltrator and criminalizing its disclosure according to the cases specified by law (Law No. 25-14, 2025, Articles 125–126).

This protection contributes to providing the necessary conditions for executing the operation more securely and effectively, and enhances the possibility of resorting to this method in confronting criminal activities that are difficult to penetrate by traditional means.

Thus, it can be said that Law No. 25-14 enhanced the effectiveness of investigation methods by combining the diversity of tools, the capacity to reach closed criminal environments, the possibility of documenting outcomes, subjecting the operation to legal supervision, and providing necessary protection for those executing it. However, these elements do not mean that effectiveness has become absolute; rather, it remains bound by legal limits that constitute part of the very nature of these tools.

3.2. Limits of the Effectiveness of Investigation Methods and Requirements for Achieving Balance

Despite the practical importance of special investigation methods, their effectiveness may decline or turn into a source of legal problems if used outside the boundaries drawn by the legislator. Therefore, an objective evaluation of these tools requires identifying the limits that should govern their use—not as restrictions impeding search bodies’ work, but as guarantees ensuring the procedure remains within the purpose for which it was enacted.

Foremost among these limits is respecting the scope, duration, and content of authorization. Authorization represents not a mere general license to use a specific tool, but defines the framework within which the operation should occur. Consequently, exceeding its scope, continuing execution after the expiration of its duration, or using the tool to achieve a purpose different from that for which authorization was issued may affect the legality of the procedure and the propriety of resulting outcomes.

Furthermore, protecting private life and individual freedoms emerges as one of the most important limits to be observed when using special investigation tools—particularly those allowing access to correspondence, recording sounds, or capturing images. The more capable a tool is of reaching the private sphere of individuals, the greater the necessity to adhere to legal controls governing its use, thereby achieving proportionality between the severity of the crime and the tool used to investigate it.

Added to this is the boundary line between uncovering crime and incitement to commit it, which is among the most delicate limits posed by the infiltration operation. The infiltrator’s success in integrating into the criminal environment does not imply granting him absolute freedom to direct the conduct of persons under investigation. Law No. 25-14 explicitly affirmed that the infiltrator may not perform acts constituting incitement to commit crimes, and attached nullity thereto (Law No. 25-14, 2025, Article 121). This provision confirms that the purpose of infiltration is uncovering existing criminal activity, not creating a crime that was non-existent to begin with.

The limits of effectiveness also appear in the probative force of results obtained from investigation. Not everything obtained during an investigation operation automatically converts into decisive evidence; rather, it remains subject to rules governing proof and to the judge’s discretionary power. This is affirmed by the framework of reports and statements, which distinguishes between mere investigative information and evidence granted special probative force by law, in addition to subjecting evidence presented before the judiciary to debate and evaluation (Law No. 25-14, 2025, Articles 349, 351–352).

Accordingly, the criterion of effectiveness should not be based solely on the quantity of information gathered or the number of persons apprehended, but must take into account the quality of results obtained, the propriety of collection procedures, and their capacity to endure through the judicial process until the adjudication of the case. A procedure leading to apprehending a suspect, but conducted in a manner violating legal conditions and weakening the probative force of obtained results, does not achieve required effectiveness in a comprehensive legal sense.

Hence, the true effectiveness of special investigation methods can be defined as a dual-dimensioned effectiveness: a first dimension consisting of practical or security efficiency—that is, the tool’s capacity to uncover crime and reach its perpetrators; and a second dimension consisting of legal and evidentiary efficiency—that is, the capacity of results obtained from the tool to endure within criminal proceedings as legal evidence admissible for judicial evaluation.

On this basis, the relationship between effectiveness and legality is not one of conflict, but of complementarity. Legality does not negate investigation effectiveness, but grants it a legal framework protecting its outcomes from challenge and enhancing its capacity to achieve its ultimate goal. Likewise, judicial supervision should not be viewed as an element restricting search and investigation bodies, but as a mechanism ensuring that results obtained by special tools convert into evidence reliable for constructing a criminal judgment.

Thus, the final evaluation of investigation methods under Law No. 25-14 leads to the conclusion that true effectiveness is not achieved merely by expanding crime detection capacity, but by striking a balance between the requirements of detection and apprehension on one hand, and the imperatives of legality and evidence integrity on the other. Whenever a tool manages to achieve both goals together—uncovering criminal activity while guaranteeing the legality of the evidence obtained therefrom—it approaches achieving the effectiveness desired in contemporary criminal policy.

Conclusion

Analysis of criminal investigation methods in light of Law No. 25-14 showed that the evolution of crime and the complexity of its commission methods have generated an increasing need for research and investigation means capable of reaching criminal activities that are difficult to uncover through traditional means. The Algerian legislator responded to this evolution by regulating a set of special investigation methods, allowing search and investigation bodies to confront serious and complex crimes, while subjecting the use of these means to a set of controls aimed at guaranteeing their legitimacy and the integrity of their outcomes.

It became clear that the issue does not merely relate to the extent of these means’ capacity to reach perpetrators, but extends to the extent of the capacity of the outcomes obtained from them to endure within the judicial process as legitimate evidence subject to debate and evaluation. This appears more clearly in the infiltration operation, which is based on deception, concealment, and the use of an assumed identity, making it one of the most sensitive investigation methods in terms of balance between the requirements of crime detection and adherence to the limits of procedural legality.

First: Results

The study reached a set of results, the most important of which can be summarized as follows:

• Traditional research and investigation means are no longer sufficient, in all cases, to confront contemporary patterns of criminality, especially crimes characterized by organization, secrecy, and concealment, which justifies resorting to more specialized investigation methods.
• Law No. 25-14 established special investigation methods within a legal framework aimed at enabling search and investigation bodies to confront complex crimes, while subjecting the use of these means to specific procedural conditions and controls.
• Infiltration occupies a distinguished position among special investigation methods, given its nature that allows the infiltrator to integrate into the criminal environment and monitor the activity under investigation from within, thereby enabling access to information that may be impossible to obtain through external means.
• Infiltration is associated with a specific nature of procedural deception, based on illusion, concealing the real capacity of the infiltrator, and using an assumed identity; however, these means do not represent an end in themselves, but are used within the limits of the legitimate purpose of investigation.
• The Algerian legislator established a clear boundary between legitimate procedural deception and incitement to commit a crime, as it permitted the infiltrator to use the necessary means of illusion to execute his mission, and conversely prohibited him from performing acts constituting incitement to commit crimes, attaching nullity thereto (Law No. 25-14, 2025, Article 121).
• The effectiveness of investigation methods is not measured merely by their capacity to reach or apprehend suspects, but is determined as well by their capacity to produce results that can be soundly integrated into the evidentiary process.
• The legitimacy of an investigation method does not, in itself, lead to granting the resulting evidence absolute probative force, but renders it fit to enter the sphere of evidence that may be judicially presented, debated, and evaluated, while the determination of its evidentiary value remains subject to the judge’s conviction.
• The integrity of evidence obtained from investigation methods is linked to the integrity of the procedure that led to it; respecting the legal basis of the procedure, the competent authority, duration, scope of authorization, and manner of execution and documentation represent essential elements in guaranteeing the legitimacy of evidence.
• Judicial supervision represents an essential guarantee for achieving balance between the effectiveness of research and investigation on one hand, and respect for rights, freedoms, and procedural legality on the other, thereby preventing special means from turning into unlimited powers.
• The study concluded that the true effectiveness of special investigation methods is of a dual nature; it is a field effectiveness consisting in uncovering criminal activity and reaching its perpetrators, and an evidentiary effectiveness consisting in producing legitimate, sound, and admissible evidence within the framework of criminal proceedings.

Accordingly, the relationship between investigation effectiveness and the probative force of evidence is not an incidental relationship, but represents a logical extension of the whole procedural process; whenever the method is more adherent to the law, its outcomes are more capable of enduring within the judicial process, which makes procedural legality an element of effectiveness rather than a constraint separate from it.

Second: Recommendations

Based on the results reached, a set of recommendations can be presented that would support the effectiveness of special investigation methods and enhance the integrity of their outcomes, as follows:

• Enhancing specialized training for judicial police officers and agents in the field of special investigation methods, including legal, technical, and practical aspects, with special attention given to the infiltration operation and means used in the digital environment.
• Supporting mechanisms of judicial supervision over the execution of special investigation methods, guaranteeing respect for the scope, duration, and specified purpose of authorization, and preventing the exceeding of legal boundaries established for the operation.
• Enhancing specialized training in distinguishing between legitimate procedural deception and unlawful incitement to commit a crime, given the direct impact of this distinction on the integrity of the procedure and the evidentiary value of outcomes obtained from it.
• Developing mechanisms for documenting and preserving the results of investigation operations, particularly recordings, images, and data of an electronic nature, guaranteeing the integrity of the evidence’s source, maintaining its content, and ensuring the possibility of verifying and debating it before the judiciary.
• Enhancing coordination between bodies in charge of research and investigation and competent judicial bodies, allowing for achieving a greater degree of harmony in executing special procedures and evaluating their outcomes within their established legal framework.
• Continuing to develop the legislative and regulatory framework for investigation methods in response to the continuous change in crime patterns, particularly crimes committed in the digital environment, while maintaining balance between the imperatives of combating crime and respect for basic rights, freedoms, and fair trial guarantees.

References:

First: Legal Texts

• People’s Democratic Republic of Algeria. (2025). Law No. 25-14 dated 9 Safar 1447 corresponding to August 3, 2025, containing the Code of Criminal Procedure. Official Gazette of the People’s Democratic Republic of Algeria, Issue 54, August 13, 2025.

Second: Scientific Articles

• Rouis, Abdelkader. (2017). Special search and investigation methods and their probative force in criminal proof. Algerian Journal of Law and Political Science, 2(1), 38–50.
• Zouzou, Houda. (2014). Infiltration as an investigation method in the Algerian Code of Criminal Procedure. Cahiers de Poitique et de Droit, 6(11), 115–124.
• Ouaddai, Ezzeddine. (2018). Infiltration as a special search and investigation method in light of Algerian and comparative criminal procedure law. Academic Journal of Legal Research, 8(3), 200–217.
• Ghezioui, Henda, & Lesledj, Nawal. (2021). Infiltration: A mechanism for searching for criminal evidence in contemporary criminal legislation. Comprehensive Journal of Law, 1(1), 145–159.
• Ayadi, Adel, & Khedidji, Ahmed. (2024). The probative force of evidence obtained through illegal means in criminal proof. International Journal of Legal and Political Research, 8(2), 129–139.
• Matmati, Raouia, & Benadida, Nabil. (2025). The infiltration operation in light of Code of Criminal Procedure 25-14. Journal of Human Rights and Public Freedoms, 10(2), 397–427.
• Touati, Basma. (2026). Special investigation methods: An approach in light of Code of Criminal Procedure No. 25-14. Academic Journal of Legal and Political Research, 10(2), 485–497.