I believe an S34 command has to due with British or UK law proceedings when the relate to interrogating a suspect in a crime.  When a suspect under very limited conditions, is silent regarding information that could incriminate him Jurors, and Judges may draw inference from that silence regarding the suspects guilt or innocence.  The command may be to gather evidence to prove that the suspect had reason to maintain silence else he or she would have aided in their own resulting conviction.