Coercion works, in the sense that it produces speech. What it does not produce is reliable information, and the international standard is built around that distinction rather than around decency alone.
Prohibited, everywhere, with no exception for urgency. Torture and cruel, inhuman or degrading treatment; threats against the person or their family; prolonged questioning designed to exhaust; denial of food, water, sleep, a lavatory, or medical care. The prohibition is absolute under the Convention against Torture — not a rule that bends when the case is serious.
Deception is not neutral either. Fabricated evidence and false claims about what others have said produce false accounts from innocent people, and they contaminate true accounts beyond repair.
Vulnerability changes what a fair interview looks like.
- Children need a specially trained interviewer and, in most systems, an appropriate adult. A child answers to please the adult asking.
- Trauma disorders sequence and time. Gaps and a story that does not run in order are what a truthful traumatic memory looks like; treating that as inconsistency is a common and expensive error.
- Language. A qualified interpreter, not a relative and not a colleague who "speaks a bit". Interpret in the first person, and let the interpreter say when something has no equivalent.
- Disability, illness, intoxication, injury. If someone cannot understand the questions or the consequences, the interview waits.
Repetition is a harm and a cost. Each retelling both distresses the person and degrades the account. Ask what they have already told, and to whom, before asking them to say it again.
Source. The Méndez Principles, Principles 2–4, https://interviewingprinciples.com/ ; OHCHR, Istanbul Protocol (revised), https://www.ohchr.org/sites/default/files/documents/publications/2022-06-29/Istanbul-Protocol_Rev2_EN.pdf ; and the Murad Code for survivors of systematic sexual violence, https://www.muradcode.com/murad-code
What this is not. Reading, not training, and not legal advice.