The American lawyer Gerald Lefcourt had to explain to the British interviewer on the BBC radio evening programme PM what was meant by the term 'perp walk' when he used it on-air (listen again for another week here - it's about 32 mins in).
Lefcourt said that he and many others were appalled at the treatment meted out by the police to Dominique Strauss-Kahn. Strauss-Kahn has not been tried or convicted, but the police have allowed the media to see him in handcuffs and looking dishevelled and unshaven after hours of questioning. This is what is meant by a perp walk, where perp is short for perpetrator. Lefcourt regards this as unethical behaviour and that it can affect a jury's attitude, as it gives the impression of a guilty person.
Although we do not use the expression 'perp walk' in Britain, it is in the OED. It is under the entry for 'perp'. The definition of 'perp walk' in the Dictionary is: "a march into or out of a police car, courthouse, etc., that a person in police custody is made to perform for the benefit of the news media". It is described as US slang, and the first recorded citation is from 1986. The first mention of 'perp' on its own was a few years earlier, in 1981.
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