The Chief Magistrate’s Practice Direction No 5 of 2005 requires that summonses (or subpoenas) for documents must be raised on the contest-mention date. (This doesn’t apply to disclosure required by Schedule 2 Clause 1A of the Magistrates Court Act 1989.)
Sometimes, the material sought is handed over voluntarily. In other cases, after discussion between the parties it’s clear the documents sought won’t help the accused, and the subpoena isn’t pursued.
If a subpoena is issued after contest-mention, the Practice Notice requires that it’s returnable at a special-mention before the contested hearing date, unless the Court orders otherwise. This is to avoid time wasting time at the hearing, from preliminary arguments about the release of documents, and then waiting as Counsel inspects the documents while everyone else twiddles their thumbs.
The Criminal Procedure Act 2009 commences operation on 1 October 2009. Sections 41 and 42 will require the prosecution to disclose a slightly greater range of material than at present, and explicitly impose a continuing obligation of disclosure.
Section 363 will permit the prosecution to withhold material when required or permitted by law, but otherwise doesn’t derogate from the general disclosure obligations.
These provisions might reduce the use of subpoenas issued by accused people, by encouraging the prosecution to engage in automatic and ongoing disclosure, though s 336 will provide for their use under the new Act.