The police have the power to ask questions before charging a person. Questioning may be informal (for example, by way of conversation) or formal (for example, by way of a record of interview). After being charged, the person should only be questioned where necessary to prevent loss to some other person or body, to recover property, or if fresh charges are being laid against them.
Under the Criminal Law (Detention and Interrogation) Act 1995, a police officer can detain a person for a reasonable time for the purposes of questioning the person, or carrying out investigations in which the person participates, in order to determine his or her involvement, if any, in relation to an offence. A reasonable time also includes the time it takes to transport and bring a person before a magistrate or justice. What constitutes a reasonable time will depend on a number of factors, enumerated under section 4(4) of the Act.
What is a caution?
Before questioning a suspected person, the police should caution them that no questions need to be answered but that any answers given may be used in evidence. If the case goes to court, the police may use evidence of such caution to show that what the accused said afterwards was said freely and voluntarily. A statement taken in the police station will conclude with questions about whether or not a caution was given and understood and whether the statement was made voluntarily. If no caution was given, this does not mean that statements made cannot be used.
Whether or not the court will use statements given without a caution as evidence is at the discretion of the court.
Written admissions are sometimes written by the arrested person and signed, or they are typed or written out by a police officer and signed by the arrested person. Written statements can be used as evidence in a court of law. As with verbal statements, it is at the discretion of the court to decide to use or not use evidence if a defendant challenges the admissibility of the evidence, alleging an abuse of police power.