Interrogation (also called questioning) is interviewing as commonly employed by law enforcement officers, military personnel, intelligence agencies, organized crime syndicates, and terrorist organizations with the goal of eliciting useful information, particularly information related to suspected crime. Interrogation may involve a diverse array of techniques, ranging from developing a congenial rapport with the subject to torture.

Deception can form an important part of effective interrogation. In the United States, there is no law or regulation that forbids the interrogator from lying about the strength of their case, from making misleading statements or from implying that the interviewee has already been implicated in the crime by someone else. See case law on trickery and deception (Frazier v. Cupp).

In 2021, Illinois became the first state to ban police officers from lying to minors during interrogations.

As noted above, traditionally the issue of deception is considered from the perspective of the interrogator engaging in deception towards the individual being interrogated. By the 2000s, information began appearing in research studies on effective interview methods used to gather information from individuals who score in the medium to high range on measures of psychopathology, and who exhibit deception with interrogators.

The major aim of this technique is to investigate to what extent verbal and non-verbal features of liars' and truth-tellers' behaviour change during the course of repeated interrogations. It has shown that liars display significantly fewer smiles, self-manipulations, pauses, and less gaze aversion than truth-tellers. According to Granhag & Strömwall, there are three approaches to non-verbal deceptive behavior. The first is the emotional approach, which suggests that liars will alter their behaviors based on their own emotional feelings. For example, if a subject is lying and they begin to experience guilt, they will shift their gaze. The second approach is the cognitive approach, which suggests that lying requires more thought than telling the truth, which in turn, may result in a liar making more errors in speech. Lastly, the attempted control approach suggests a subject who is lying will attempt to be seemingly normal or honest, and will try to adjust their behaviors to make themselves believable.

Good cop, bad cop is a psychological tactic used in negotiation and interrogation, in which a team of two interrogators take apparently opposing approaches to the subject. One adopts a hostile or accusatory demeanor, emphasizing threats of punishment, while the other adopts a more sympathetic demeanor, emphasizing reward, in order to convince the subject to cooperate.

In the People's Republic of China, the "wheel battle" (chelunzhan) tactic involves "unrelenting continuous interrogation by multiple rotating interrogators".

The use of drugs in interrogation is both ineffective and illegal.^[where?] The Body of Principles for the Protection of All Persons under Any Form of Detention or Imprisonment (adopted by the UN General Assembly as resolution 43/173 of 9 December 1988) forbids "methods of interrogation which impair the capacity of decision of judgment." Furthermore, the World Medical Association and American Medical Association, for example, both forbid participation by physicians in interrogations.