What Are the Mendez Principles on Effective Interviewing?

The Mendez Principles are a set of six principles on effective interviewing for investigations and information gathering, published in 2021. They were developed by an international steering committee

By Murder Book Editorial TeamPublished by Gungrounds, the studio making Murder BookPublished 3 October 2026Updated 3 October 2026

The Mendez Principles are a set of six principles on effective interviewing for investigations and information gathering, published in 2021. They were developed by an international steering committee of fifteen experts, co-chaired by Juan Mendez, the former United Nations Special Rapporteur on Torture, and Mark Thomson, the former Secretary General of the Association for the Prevention of Torture. The principles offer a science-based, human-rights-compliant alternative to coercive interrogation methods. They apply to all interviews conducted by law enforcement, military, intelligence and other state actors, and they draw on the same body of research that supports information-gathering interviewing more broadly.

Key takeaways

The Mendez Principles were published in 2021 as an international standard for non-coercive investigative interviewing.
They were developed by fifteen experts from more than forty countries, drawing on science, law and ethics.
The six principles cover foundations, practice, vulnerability, training, accountability and implementation.
Research shows that rapport-based interviewing produces more reliable information and fewer false confessions than coercive methods.
The principles do not ban firm or challenging questioning; they ban coercion, torture and methods that undermine reliability.

Why were the Mendez Principles created?

Despite decades of research showing that coercive interrogation methods are unreliable and increase the risk of false confessions, many countries still use accusatorial or pressure-based techniques. Kassin and Gudjonsson (2004) reviewed the confession literature and identified multiple mechanisms through which coercive methods produce false admissions, including psychological pressure, false evidence ploys and prolonged questioning of vulnerable individuals.

The Mendez Principles were created to fill a gap. International law already prohibits torture and cruel treatment, but it offered little practical guidance on what should replace those methods. The steering committee spent four years consulting with more than eighty experts from over forty countries to produce a framework grounded in science, law and ethics. The Association for the Prevention of Torture, the Anti-Torture Initiative at American University and the Norwegian Centre for Human Rights jointly published the result.

What are the six principles?

The principles are organised around six themes:

1. Foundations

Effective interviewing is based on communication and rapport rather than coercion. The goal is to obtain accurate and reliable information. This aligns with the meta-analytic finding by Meissner, Redlich, Michael, Evans, Camilletti, Bhatt and Brandon (2014) that information-gathering approaches produce more true confessions and fewer false confessions than accusatorial methods.

2. Practice

Interviews should be conducted by trained professionals who use evidence-based methods. Interviewers should plan their approach, ask open-ended questions, listen actively, disclose evidence strategically and avoid leading or suggestive questioning. These practices reflect the core of models such as the PEACE framework and the cognitive interview.

3. Vulnerabilities

Certain groups are at heightened risk during questioning, including children, people with intellectual disabilities, people with mental health conditions and those unfamiliar with the language or legal system. The principles call for additional safeguards when interviewing vulnerable individuals. Research by Kassin and colleagues (2010) has shown that vulnerable suspects are disproportionately represented among documented false confessions.

4. Training

Effective interviewing requires sustained, evidence-based training and ongoing professional development. The principles emphasise that a short course is not enough; interviewers need regular practice, feedback and supervision. Snook, Eastwood, Stinson, Tedeschini and House (2010) found that Canadian police training in suspect interviewing relied heavily on the Reid Technique and recommended a shift toward scientifically grounded methods, a recommendation the Mendez Principles echo at the global level.

5. Accountability

Interviews should be documented, preferably by audio or video recording, to allow review and ensure compliance. Recording protects both the interviewee and the interviewer. Research on recording interrogations suggests that electronic recording reduces disputes about what was said and provides a check against coercion.

6. Implementation

Governments and institutions should adopt policies, laws and institutional frameworks that support non-coercive interviewing. The principles call for systemic change, not just individual training.

How do the Mendez Principles relate to existing interviewing models?

The principles are not a specific interviewing technique like PEACE or the cognitive interview. They are a set of overarching standards that any compliant technique should meet. The PEACE model, developed in England and Wales in the 1990s, and the cognitive interview, developed by Fisher and Geiselman for witness interviews, both align with the Mendez Principles because they are rapport-based, non-coercive and grounded in psychological research.

Vrij, Meissner, Fisher, Kassin, Morgan and Kleinman (2017) reviewed the psychological evidence on interrogation and concluded that rapport-based methods are more effective than coercive ones at eliciting accurate information. The Mendez Principles translate that conclusion into a framework that governments and agencies can adopt.

Coercive methods	Mendez-compliant methods
Assume guilt before questioning	Remain open to all explanations
Use pressure to overcome resistance	Use rapport and open questions to gather information
May involve deception or threats	Exclude coercion and deceptive practices
Higher false confession risk	Lower false confession risk
Limited training standards	Require evidence-based training and supervision
May lack recording	Require documentation and accountability

Are the Mendez Principles legally binding?

Not directly. The principles are a set of guidelines, not a treaty or statute. However, they draw on binding international law, including the United Nations Convention Against Torture and the International Covenant on Civil and Political Rights. They are designed to be adopted voluntarily by governments and institutions, and they provide a benchmark against which interviewing practices can be measured.

Several countries and organisations have already begun referencing the principles in policy discussions. The principles have also attracted attention from academic researchers studying how interviewing reform spreads across jurisdictions. For a broader comparison of the accusatorial model and the information-gathering alternative the principles support, see Accusatorial vs Information-Gathering Interrogation.

How does Murder Book connect to non-coercive interviewing?

Murder Book: The Art of Interrogation is an upcoming narrative interrogation game from Gungrounds, an independent studio in Zagreb, Croatia. Development screenshots show a technique menu that includes Build Trust, described as "fostering an environment where the suspect feels comfortable and secure enough to communicate openly." That aligns with the Mendez Principles' emphasis on rapport as the foundation of effective interviewing.

The game also lists more confrontational techniques such as Confrontation and Bluffing. Players appear to choose how they question suspects, and development materials show a branching case map with different endings. The design suggests that the approach a player takes may shape the outcome, reflecting the real-world finding that different methods produce different results, not all of them reliable.

Murder Book is in development for PC (Steam) and mobile, with release currently planned for the end of Q2 2027.