invited witness; unsworn witness
In Japanese legal proceedings, a person who appears before a committee or court to provide testimony but is not under oath. Distinct from a sworn witness (証人).
I was summoned to the Diet committee as an unsworn witness.
person of interest; voluntary interviewee
Used in criminal investigations for someone who is questioned voluntarily, not as a suspect or under arrest. Often appears in news reports.
The police interviewed him as a person of interest in the case.
expert advisor; consultative expert
A specialist invited to give opinions or advice in legislative or administrative settings, not as a formal witness.
The expert gave an opinion as a consultative advisor.