Everyone should carry a copy of this case, Richardson v Chief Constable West Midlands. It makes plain that on a voluntary attendance the police cannot presume to arrest. They must consider a voluntary interview. PACE clearly states that the police need to establish the necessity for an arrest. Without a compelling reason like DNA or fingerprints at the scene of a crime there is unlikely to be such a necessity and voluntary attendances should be dealt with by way of a voluntary interview.

Read the full text here: Richardson v West Midlands Police