The police may ask you to participate in a line up, where the A person who can provide direct information based on their own knowledge about a relevant fact in issue, and appears in court to do this. is asked to identify the person who committed a crime. The police cannot force you to participate in an A police "line up" held so a witness to an offence can try to identify a suspect among other people of similar appearance.. If you participate in such a line up, you risk being mistakenly identified as the A person who commits an offence.. You should refuse to participate in any A police "line up" held so a witness to an offence can try to identify a suspect among other people of similar appearance. or line-up until you have spoken to a lawyer.