Méndez Principles On Effective Interviewing

The Principles on Effective Interviewing for Investigations and Information Gathering, also known as the Méndez Principles, is a set of international guidelines designed to provide a concrete alternative to interrogation methods that rely on coercion. Developed by a global Steering Committee of experts, consulting an Advisory Council of specialists from over 40 countries, the Principles offer an evidence-based framework for interviewing across a wide range of scenarios — from routine policing to complex investigations. They apply to interviews conducted by law enforcement, intelligence, military, immigration, customs, and related administrative authorities, and cover interactions with suspects, witnesses, victims, and other persons of interest. Coordinated by the Association for the Prevention of Torture, the Anti-Torture Initiative and the Norwegian Centre for Human Rights, the final text is grounded in a scientific research base, documented good practices, established international law and professional ethics. It was published in 2021 and now available in more than 15 languages.

The document is structured around six principles:
# Effective interviewing is instructed by science, law and ethics.
# Effective interviewing is a comprehensive process for gathering accurate and reliable information while implementing associated legal safeguards.
# Effective interviewing requires identifying and addressing the needs of interviewees in situations of vulnerability.
# Effective interviewing is a professional undertaking that requires specific training.
# Effective interviewing requires transparent and accountable institutions.
# The implementation of Effective Interviewing requires robust national measures.

These are called the Méndez Principles to honour the former UN Special Rapporteur on Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment, Juan E. Méndez. The document grew from a thematic report submitted by Prof. Méndez to the United Nations (UN) General Assembly in 2016 calling for the development of international standards for interviews based on scientific research, legal safeguards and ethical standards. The Méndez Principles represent the realization of that call.

Michelle Bachelet, then UN High Commissioner of Human Rights, opened the launch event for the document on 9 June 2021. Since that date, more than 50 countries from all regions have supported them, and a growing body of UN, regional and national documents/jurisprudence reference the document.APT
References to the Principles on Effective Interviewing for Investigations and Information Gathering (Méndez Principles)
by United Nations, regional and national documents/jurisprudence, 7 June 2025. International projects have been launched to implement the principles to expand the global trend toward non-coercive interviewing.Establishing Networks to Implement the Principles on Effective Interviewing for Investigations
ImpleMéndez -- CA22128, (Start date 5 October 2023 End date 4 October 2027). Moreover, ''The UN Manual on Investigative Interviewing for Criminal Investigation'' was built on the foundations of the Méndez Principles and validated by three UN bodies in November 2023 to continue the shift away from confession-driven methods.

Background and Purpose

International law universally condemns torture and ill-treatment as an absolute prohibition. The Méndez Principles offer tools by which to realize this obligation in the context of gathering information from an individual. While they have not been officially endorsed by a UN body, they are similar to other protocols, such as the Mandela Rules, Istanbul Protocol and Minnesota Protocol, in that this document is an authoritative resource on law and practice which is not legally binding. They are rooted in practical scientific research on how best to gather factual information, combining legal norms with a comprehensive guide for conducting interviews that uphold accuracy and professionalism.

Notably, while the lineage of the methods can be traced globally, the analogous approach of investigative interviewing has been developing across Europe (and beyond) for decades; these effective, legal and ethical methods are (starting to be) employed by law enforcement and security personnel across a variety of countries. Additionally, rigorous scientific research on the question of effectiveness has been pursued by the High-Value Detainee Interrogation Group (HIG) in the United States significantly contributing to the body of evidence. In contrast, Darius Rejali observed in his comprehensive study of the matter that, " ere may be secret, thorough reports of torture's effectiveness, but historians have yet to uncover them for any government. Those who believe in torture's effectiveness seem to need no proof and prefer to leave no reports."

This document responds to the persistent challenge of torture and ill-treatment during investigations and intelligence gathering, including in situations of armed conflict or public emergency, despite an extensive international legal framework prohibiting such practices. They build on a vast scientific literature that establishes rapport-based, non-coercive interviewing techniques as the most effective means of gathering accurate and reliable information. They also draw on extensive literature underscoring the ineffectiveness and counter-productive property of torture and abuse.

The global consortium of experts who crafted the text came from various fields, including law enforcement, psychology, national security, military, intelligence gathering, human rights, and criminology. By operationalizing the presumption of innocence, the Principles contribute to more just, safe, and inclusive societies, aligning with the UN Sustainable Development Goals.

Interviewing as a Comprehensive Process

The Méndez Principles define effective interviewing not as a single event, but as a process that spans the entirety of an individual's interaction with investigative or information-gathering authorities. This process begins the moment a person is identified as someone from whom information is sought, continues through the planning and conduct of the interview itself, and concludes only after the interviewer assesses both the process and the information obtained. The treatment of the interviewee throughout—before, during, and after the interview—is considered integral to the overall integrity of the process.

Recognizing that interviewing involves human beings, human behaviors, and human rights, the Principles emphasize that the process must remain adaptive. Rather than pursuing confessions or rigid objectives, interviewers are encouraged to exercise professional judgment, maintain flexibility, and focus on eliciting accurate and reliable information. The objective is never to confirm an interviewer's beliefs or assumptions, nor to pressure the interviewee into cooperation, but to produce accounts that are both factually sound and legally defensible.

Accuracy in interviewing means obtaining a description of events that is as free as possible from error, omission, or distortion. Given the limits and fallibility of human memory, interviewers are trained to elicit and preserve accounts that are complete, coherent, and grounded in the interviewee's recollection of actual events. Reliability, meanwhile, refers to whether the information obtained—freely and without coercion—is likely to withstand scrutiny, including in legal proceedings or operational assessments. These qualities are essential to any credible investigative or information-gathering process.

To be effective, the interview process relies on careful preparation and planning, the consistent application of safeguards, the creation of a non-coercive environment, and the establishment of rapport. The Méndez Principles incorporate the latest insights from research on human memory, and also depend on lawful and scientifically supported questioning techniques, active listening, and rigorous post-interview assessment. They underscore that every interview is different, and interviewers must remain attentive to context and guided by professional judgment throughout. Empirical studies with incarcerated individuals have found that rapport-based interviewing techniques, compared to aggressive or coercive methods, lead to greater cooperation and more complete and accurate accounts.

Legal and procedural safeguards grounded in international law are embedded throughout the interviewing process. Their implementation supports both human rights and evidentiary reliability. International and regional bodies mandated to prevent torture and ill-treatment have consistently underscored the importance of safeguards that protect individuals from the outset of police custody. Among these, the “trinity of rights” — access to a lawyer, access to a doctor, and the right to notify a third party of your detention — are considered essential early safeguards. As individuals move through the justice system, additional procedural protections such as the presumption of innocence, the right to remain silent, and the exclusion of evidence obtained through ill-treatment remain critical for ensuring fairness and legal integrity. Other safeguards include informing individuals of their rights and the reasons for arrest, providing interpretation services, ensuring access to medical care, registering detainees, fully recording interviews, allowing individuals to review and sign interview records, and facilitating access to judicial review mechanisms, including habeas corpus. Collectively, these measures help ensure that interviews are conducted in a manner that respects human rights while supporting the collection of accurate and reliable information. In May 2025, a statement from the Co-Chairs of the Méndez Principles Steering Committee of Experts, Juan E. Méndez and Mark Thomson, reiterated the importance of the legal and procedural safeguards as an integral part of effective interviewing.Upholding the Added Value of the Méndez Principles
May 1 2025

Formal Structure

Formally, the document has six sections, each addressing one of the six principles for effective interviewing. Each section consists of advice, counsel, and practical steps to be taken.

Principle 1 – On Foundations

This initial Principle establishes the groundwork for effective interviewing practices with three critical pillars: scientific foundations, legal grounds, and widely accepted professional ethics. Together, these components provide the basis for ensuring that interviews are conducted in a manner that upholds all the central elements at stake.

Principle 2 – On Practice

The second Principle outlines a process for conducting interviews, prioritizing the collection of accurate and reliable information. It underscores the importance of legal safeguards, ensuring a non-coercive environment before the interview, establishing and maintaining rapport during the interview, and conducting assessment and analysis at the interview's conclusion.

Principle 3 – On Vulnerabilities

Recognizing the inherent power imbalance that all interviewees face, this Principle highlights the interview as a situation of vulnerability. It also provides guidance on addressing situations of heightened vulnerability and offers a framework for assessing and mitigating potential risks during interviews.

Principle 4 – On Training

Effective interviewing relies on well-trained professionals. It emphasizes the need to train interviewers and promote continuous professional development to ensure that interviewers are able conduct effective interviews.

Principle 5 – On Accountability

Accountability is a cornerstone of effective interviewing practice. This Principle outlines institutional procedures and review mechanisms, effective record-keeping, prevention and reporting of misconduct, external oversight and independent monitoring, as well as processes for handling complaints, conducting investigations, and providing redress and reparations when necessary.

Principle 6 – On Implementation

The final Principle focuses on application within domestic legal frameworks. It addresses institutional culture and capacity, the role of judicial authorities, and the dissemination of these Principles to ensure their widespread adoption and consistent application.

Global Recognition, Citation and Implementation

Reference to the document has been made nearly 100 times by United Nations bodies, regional and national documents/jurisprudence, both during the drafting period of the document and after it was published in 2021. For example, the UN General Assembly passed a Resolution on torture and ill-treatment in 2022 that references the Méndez Principles and "encourages States to use them ..thereby operationalizing the presumption of innocence."UN General Assembly
UN Doc. A/RES/77/209
15 December 2022, at para 16.

Another example is found in a national court judgment in June 2024 where a judge in the highest court of Brazil, the ''Superior Tribunal de Justiça'', used the document to support his decision:

''"Faz sentido que em uma investigação preliminar não reduzida a conseguir confissões, reconhecimentos viciados e, em suma, a apontar o culpado 'a jato', sejam adotadas cautelas próprias das chamadas entrevistas cognitivas (ou eficazes). Sobre elas, é útil trazer os chamados'' Princípios Méndez''. ..Em resumo, tanto por compromissos éticos e humanitários constitucionalmente assumidos, quanto por preocupações epistêmicas com a determinação da verdade dos fatos, certo é que há sobradas razões para buscar o abandono dessa obsessão investigativa por conseguir confissões a qualquer custo, tal como observada no caso sob exame."''Superior Tribunal de Justiça (Brazil). (2024) Opinion of Minister Rogério Schietti Cruz. Appeal in Special Review No. 2123334 - MG, Rapporteur: Minister Ribeiro Dantas. Antony José de Souza Rosa vs. Public Prosecutor of the State of Minas Gerais. Brasília. Available at
GetInteiroTeorDoAcordao (stj.jus.br)

English Translation:

''"It is reasonable that in a preliminary investigation, which is not aimed at securing confessions, biased identifications, or, ultimately, hastily pinpointing a suspect, specific safeguards associated with so-called cognitive (or effective) interviews should be adopted. In this regard, it is useful to refer to the so-called Méndez Principles. ..In summary, both due to constitutionally undertaken ethical and humanitarian commitments, as well as epistemic concerns regarding the determination of factual truth, it is evident that there are ample grounds to abandon the investigative obsession with obtaining confessions at any cost, as observed in the case under review."''

This wide and growing recognition is an acknowledgment of the document's persuasive authority, validity, and quality; i.e., these bodies and organizations recognize the document as a reputable source of information or guidance within their respective spheres of influence. Reference to the document has been made by the following bodies thus far:

* UN Resolutions and Declarations
** UN General Assembly
** UN Office on Drugs and Crime
** UN Human Rights Council
* UN Human Rights Bodies, UN Treaty Bodies and Special Procedures
** UN High Commissioner for Human Rights
** UN Human Rights Committee
** UN Committee Against Torture
** UN Subcommittee on Prevention of Torture
** UN Working Group on Arbitrary Detention
** UN Special Rapporteur on Torture
* References and Resolutions by Regional Organisations and Human Rights Bodies
** African Union
** Council of Europe
** European Union
** Organization of American States
** OSCE Office for Democratic Institutions and Human Rights (ODIHR)
* References and Declarations by Human Rights Networks and Professional Associations
** Global Alliance of National Human Rights Institutions (GANHRI)
** American Bar Association (ABA)
* Within National Jurisprudence
** Colombia
** Brazil

In 2023, the European Cooperation in Science and Technology (COST) launched a project to establish networks to implement the Méndez Principles.European Cooperation in Science and Technology
CA22128 - Establishing Networks to Implement the Principles on Effective Interviewing for Investigations (ImpleMéndez), (Start date 5 October 2023 End date 4 October 2027). The project funded by the European Union has been entitled ImpleMéndez and runs through 2027. It involves a strategy of convening regional and in-country networks of researchers, practitioners and policy makers working to enable wider implementation of the principles. The project has brought together (as of June 2025) almost 350 members across in 58 countries and includes experts in policing, human rights, psychology, law, forensic linguistics, criminology, anthropology, neuroscience, political science, sociology, interpretation, and more (see https://implemendez.eu/ ).

In February 2024, a UN manual built on the foundations of the Méndez Principles was released for a policing context: ''The UN Manual on Investigative Interviewing for Criminal Investigation.''UN Department of Peace Operations, UN Office of the High Commissioner for Human Rights, UN Office on Drugs and Crime
The Manual on Investigative Interviewing for Criminal Investigation
(February 2024), at para 1.1, 5.1, 5.2, Box 2 and fn 1. It was approved by more than 30 UN experts and state representatives and is the product of a collaborative effort between the UN Department of Peace Operations, the Office of the High Commissioner for Human Rights, and the UN Office on Drugs and Crime. The manual serves as a guiding document for the United Nations Police officers in their mandated roles, and establishes a resource for police development and capacity-building across the UN system.

References

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External links

Official website for the Méndez Principles

Compilation of UN, regional and national references to the Méndez Principles (APT, 2025)

UN Manual on Investigative Interviewing for Criminal Investigation (2024)

APT page on the Méndez Principles

ImpleMéndez – COST Action to implement the Méndez Principles

Human rights instruments
Interrogation techniques
Human rights
United Nations
Ethics
Police
Torture
International law