The Méndez Principles: Emergence and Global Expansion of Non-Coercive Interviewing

CERL is pleased to present this article (and the entire Just Security series) based on the newly-released Principles on Effective Interviewing for Investigations and Information Gathering, also known as The Méndez Principles. Named for Juan Méndez, the former UN Special Rapporteur on Torture who in 2016 called for the creation of a universal protocol for lawful and humane interviewing standards, the principles provide guidance on conducting non-coercive and rapport-based interviews with legal and procedural safeguards. CERL has been an advocate of Mr. Méndez’s call for the protocol and welcomed him as the keynote speaker at CERL’s 2018 conference on interrogation and torture.–Claire O. Finkelstein, CERL Academic Director


The Méndez Principles: Emergence and Global Expansion of Non-Coercive Interviewing, by Ray Bull, Asbjørn Rachlew, and Mary Schollum, was originally published on Just Security.

(Editor’s note: This article is part of a Just Security series on the newly released “Principles on Effective Interviewing for Investigations and Information Gathering,” an expert-led initiative responding to a 2016 appeal to the U.N. General Assembly by then-U.N. Special Rapporteur Juan E. Méndez to develop such standards. The series outlines the origins and the scientific, legal, and ethical underpinnings of the guidelines, also known as the “Méndez Principles” in honor of its co-chair.)

Interviewing (or “interrogating”) those possibly involved in criminal activity is a core function of police work. Traditionally, however, little time has been spent on improving this vital task, and it has often been carried out based on interviewers’ gut feelings, intuition, and copying peers. Moreover, organizational culture has strongly influenced practice. With attention on such issues over the past four decades and the lifting of the shroud of secrecy from the interview room, we now see more clearly that interviewers in many jurisdictions have not had a specific methodology to follow. This has created an environment that has allowed, or sometimes even fostered, the use of intimidation, coercion, and psychological manipulation.

Three countries where we work as, respectively, a professor of psychology, a police superintendent, and a criminal justice and policing consultant, illustrate the change from a focus on getting a confession, to “investigative interviewing” — an approach which is legal, ethical, effective, and evidence-based. We have directly participated in an emergence from threatening and narrowly conceived practices, and have noted the connecting threads in the more recent shifts in institutional cultures across international borders: ongoing leadership and oversight, a change of mindset, amendments to relevant policies and procedures, comprehensive training, amendments to the legal framework where required, extended use of technology, and ongoing research and evaluation.

United Kingdom

In England and Wales in the 1970s, a number of high-profile criminal convictions were over-turned largely due to interviewer coercion. A resulting report broke new ground in utilizing information provided by psychologists, rather than contentions unsupported by research. This report led the U.K. government in 1984 to introduce the “Police and Criminal Evidence Act,” which mandated stricter controls over police questioning, including the right to legal representation for suspects, limits on detention before charge, and an audio recording of all suspect interviews. Of utmost importance, this required recording data that could be systematically analyzed.

Research studies conducted soon after tape recording became mandatory showed that police were not skilled at interviewing, they required more training, and at times, were even unaware of their lack of skill. As a result, in 1990, the Association of Chief Police Officers and the Home Office put together a working group of experienced investigators to develop up-to-date interview training. This group came up with an interview model known as PEACE, an acronym for Planning and Preparation, Engage and Explain, Account, Closure, and Evaluation.

Around the same time, a senior police officer convened a working group of detectives and psychologists (including co-author Bull) that produced a review of findings from psychology useful to the improvement of investigative interviewing — such as how memory works, and the effective use of rapport, question types, and active listening. The national team incorporated much of the contents of this review into the new PEACE training package.

These pioneering developments in relation to how suspects, as well as witnesses and victims, were to be interviewed came into effect in 1992. They involved detailed national guidance and training courses that were compulsory for police interviewers in England and Wales, and later in the whole of the U.K.

Key inputs over time have ensured that this approach remains fit for purpose. They include oversight by a national strategic steering group, national position statements developed by subject-matter experts and skilled practitioners with support from the National Crime Agency and College of Policing, regular evaluation, and further research. Since the introduction of the PEACE model to the U.K., a host of research studies in many countries has produced findings that support the use of such a method (see e.g., here, here and here).


In 1997, the Norwegian Police Service suffered a major setback. A young man was convicted but later acquitted for a murder to which he had initially confessed. The high-profile case had a large societal impact. The disputed confession was elicited by detectives who, at the time, were regarded as the best interviewers in Norway. The court-appointed experts (including Professor Gisli Gudjonsson) concluded that the style of interviewing was heavily influenced by the style in the North American literature on interrogation, where manipulation and trickery were routinely employed with one goal in mind: to obtain a confession. As Gudjonsson pointed out, the fundamental problem with the interviews was the use of isolation combined with manipulative techniques solely designed to obtain a confession from someone already presumed by the interviewing officers to be guilty.

As a consequence, the Norwegian police provided full sponsorship for two detectives to undertake postgraduate courses in the U.K. to study the conduct of investigative interviews, particularly from a forensic psychology perspective. The first dissertation written in 1999 (by co-author Rachlew) confirmed the discouraging picture presented by the experts in the murder trial, and showed that experienced detectives were passing on manipulative, confession-focused techniques to each new generation. This led to approval of the first investigative interviewing training program for the Norwegian Police Service.

An organizational shift was initiated away from interrogation tactics focused on obtaining confessions, to research-based techniques aimed at gathering accurate, reliable, and complete information. The framework is known as KREATIV, which translates in English as: Communication, Rule of Law, Ethics and Empathy, Awareness, Trust, Information, and Verified Scientific Research. In order to employ the methodology of the U.K.’s PEACE model as part of the KREATIV program, Norway invited U.K. police detectives and criminal psychologists over to provide expert advice, and also translated writings into Norwegian (e.g., on ethical interviewing) for a training program that became mandatory in 2004.

The Norwegian Police have continued to seek improvements. A notable example is that KREATIV has provided detectives with clear instructions on how, when, and all importantly why they should delay disclosure of some of the potential evidence until all plausible, alternative explanations of it have been explored within interviews. This innovative development, which was inspired by a pragmatic model for evidence evaluation, has served to change the mindset of Norwegian detectives and hence – as acknowledged by former U.N. Special Rapporteur on Torture Juan E. Méndez in his 2016 report to the United Nations General Assembly – is helping “to ensure that the presumption of innocence is respected while strengthening the case against a guilty suspect.”

The implementation of investigative interviewing in Norway was relatively swift for several reasons: 1) the drive for change came from within the police service; 2) the new methodology (and thinking style) was embraced and launched by the National University Police College; 3) it was supported by other stakeholders, including the General Prosecutor’s Office and a Supreme Court ruling; and 4) it was operated by police officers with a strong understanding of forensic psychology.

The acknowledged success of investigative interviewing in Norway has led to extensive collaborations between Norway, academia, and organizations such as the Norwegian Human Rights Centre and the Convention Against Torture Initiative. Representatives have delivered training in numerous countries over the last 10 years, including Vietnam, Indonesia, Thailand, Hong Kong, China, the Republic of Ireland, Singapore, Malaysia, Lebanon and, most recently, Nigeria. Senior leaders and practitioners in those countries have responded with both commitment and enthusiasm.

New Zealand

New Zealand Police commissioned a review of its interviewing practices in late 2004. This was due to a recognition by the police service itself of changes taking place internationally — in particular in the U.K. — but also owing to criticism from the courts of the police handling of certain interviews and calls for improvement from the police Training Service Centre. As a result, the Police Executive appointed one of the authors of this piece as a reviewer (Schollum) to examine interviewing from the inside out. Official support and resources proved vital over the two-year timeframe.

With assistance from a six-person project team for six months, the reviewer not only examined the international situation but also carried out national research which included: examination of official policies and procedures; assessment of more than 200 interviews; surveys of police officers, prosecutors, judges, and crown solicitors; extensive stakeholder consultation; a review of case law; and the pilot-testing of a week-long course delivered to more than 100 sworn officers. Of the three reports produced for the review, the most widely referenced and accessed has been the report on the literature, which covers everything from psychology, ethical interviewing, and individual techniques, to technology and training. Today, the Norwegian police have had this work translated and made required reading.

In late 2006, the reviewer’s primary recommendation was for New Zealand Police to adopt PEACE as its interviewing model. Other recommendations included policy and guidance; training, standards, and competency; technology, equipment, and interview rooms; maintenance and support; communications; and evaluation. As in the U.K. and Norway, New Zealand Police formally rejected the term “interrogation” in favor of “investigative interviewing.” The Police Executive accepted the recommendations in full, and implementation began in January 2007. (New Zealand Police is a national service that has autonomy to make its own policies; thus, information can be found on its website regarding the announcement, doctrine, and evaluation). Moreover, results of the study were deemed relevant to tribunals investigating police corruption in jurisdictions as far away as Ireland, where the reviewer was brought in as an expert witness.

Efforts over the next five years produced the policies, training material, and equipment necessary to implement the PEACE framework, and achieved the roll-out of training to frontline officers as well as appropriate training to recruits, detectives, and specialist interviewers. All changes were agreed with the courts and related criminal-justice agencies.

After that, other priorities meant that the pace set by the review and the implementation team was not maintained. Over the last few years, however, new leadership has put investigative interviewing back on the agenda. Innovations include the interviewing of domestic violence victims on mobile phones to capture accurate and full details in the moment, as well as the introduction of a dedicated team to review video statements and a high-level interviewing program for complex investigations. Furthermore, training programs and procedures on investigative interviewing are continuing to proliferate in New Zealand. For example, the Criminal Cases Review Commission (“Te Kāhui”) has recently commissioned such training for investigators and updates to their website to build public confidence.


These three national jurisdictions that have introduced legal and effective techniques of non-coercive interviewing demonstrate not only that change is possible, but that it is already happening. The “Principles on Effective Interviewing for Investigations and Information Gathering” have captured the essential elements of the investigative interviewing method we have worked with ourselves, even though the principles do not promote any specific model. They have been drafted in a manner that recognizes the fact that every State, jurisdiction, and organization is different, and has different legislation, policies, and procedures. The aim of the diverse international Steering Committee that produced the Méndez Principles was to ensure they would be applicable, as the final document notes, to “every interview, and are based in foundations of science, law and ethics that pertain in every setting.”

Our experience has shown us that sound leadership, planning, and training have been instrumental in fostering a shift in institutional culture toward a new mindset of non-coercive interviewing. When this is coupled with law enforcement officers who understand and support the change, it becomes possible to transform institutional practice.

About the Authors


CERL is grateful to Steven J. Barela, Senior Research Fellow at the University of Geneva in the Global Studies Institute, for his work in the publication of these articles on The Rule of Law Post. This work, which includes serving as Editor leading the Chairpersons’ Editorial Group of the Méndez Principles initiative, is supported by the Swiss National Science Foundation.

Mailing List


Submissions to The Rule of Law Post. Please refer to CERL’s submission guidelines for additional details on the blog post format. Should your submission be accepted, we ask that you please complete the Agreement to Transfer Copyright.

Please upload text in one document under 6 mb. Preferred format as a simple text file (.txt).

Share The Méndez Principles: Emergence and Global Expansion of Non-Coercive Interviewing on:

The Méndez Principles: Emergence and Global Expansion of Non-Coercive Interviewing