The Speaker made a statement to the House of Commons this afternoon about the Damian Green affair. (See on this my earlier commentary on the legal position.)
In his statement he states that he "regrets" that police were allowed to search Damian Green's MP's office in the House without a warrant; that the Serjeant at Arms had allowed the search by signing a consent form; and that he had known in advance about the search and Mr Green's arrest, but he had not been told that the police did not have a search warrant.
However, he is confessing to an error of procedure that he or the Serjeant at Arms did not make. The question of the Serjeant at Arms consenting (apparently inadvertently) to the entry into Mr Green's office without the prior issue of a warrant is a red herring, since the issue of a warrant for the search of the House of Commons would have been unconstitutional. In short, a warrant couldn't have been issued without consent, and if consent were to be given then there would be no need for a warrant.
The Speaker's proposal for a new protocol permitting or requiring warrants to be issued against the House is also misconceived, for the same reason. It should be resisted as comprising a gross breach of privilege. It is not for the courts to issue warrants, but for the House to permit or to refuse permission, after investigating the facts alleged by the police giving rise to the request for them to enter. Possibly he meant to institute a protocol or procedure for the issue of warrants against the personal property of individual MPs which they keep in their offices (see below). It remains to be seen what MPs think about that.
I suppose confessing to an error of procedure may be viewed as better than confessing to an error of judgement.
There remains the question of the taking away of a MP's personal property in his office (if any). That may require a warrant although it is an interesting point whether such a warrant could be issued, even with the Serjeant at Arm's or Speaker's consent. Would that require an Act of Parliament?
On the last point (whether further legislation would be needed to enable personal property of a member in his office at the House to be seized under a warrant), probably not. The Times have obtained a copy of a House of Commons Library report prepared at short notice last night. The report points out correctly that a member of Parliament is not protected from arrest within the Palace of Westminster on account of criminal conduct on his part, and that unlawful conduct engaged at in Parliament is not privileged unless it forms part of a proceeding in Parliament protected by article 9 of the Bill of Rights. This report of the Committee of Privileges also covers similar ground.
This means that in the unlikely event of Damian Green having conspired with a civil servant for the civil servant to commit misconduct in a public office, Mr Green would not be immune. However, that has not been in dispute.
This does not mean that executing a warrant to seize or examine property of the House, such as its computers and papers, in furtherance of a criminal investigation would be proper without consent of the House. It seems to me that it would not, but since this does not appear to have arisen before there are no precedents to rely on.
Much probably turns on what comprises property of the House and what comprises personal property of an individual MP. That might also make the drafting and execution of a warrant for the seizure of property within the precincts of the Palace of Westminster an exceptionally difficult exercise.
Presumably little if any personal property of Damian Green was involved as he did not, apparently, give consent to seizure of property there without a warrant1. Perhaps time will tell.
1 An issue would then arise about whether section 18 of the Police and Criminal Evidence Act 1984 applies to offices at Parliament with respect to the personal property of a MP or peer kept in his/her office, and if so whether the MP or peer "occupies or controls" the office within the meaning of that section in addition to the Parliamentary estate (clearly the Parliamentary estate does). If he/she does, then that is another reason why the issue of a warrant is an irrelevance - the police would not need one and could not be required to obtain one to examine and seize personal property.