There does not need to be a criminal offence pending for a search warrant to be issued. There only needs to be evidence that a crime could have been committed. Select committees hold the same weight as a criminal court. There are some ancient laws that are reputed to give them sentencing powers. They now rely on courts to process any wrong doing. It is a similar to the authority of the crown. We know the king can do certain things, but he won’t because of the shit storm it would cause afterwards.