The British parliament has refused to go along with a government sponsored bill to allow the detention without charge of suspected terrorists for up to three months. This was only possible because many MPs from the ruling labor party bucked Tony Blair and his cabinet on the issue. Current British law allows such detentions for two weeks.
British legislators are not addressing an abstract question here either. London was just hit with subway bombings a few months ago, and has a long history of IRA terrorist attacks.