The Tories challenged ministers yesterday to back a new Bill designed to protect householders from prosecution if they use force to defend their home from intruders.

David Davis, the shadow Home Secretary, pledged support for the Tory homeland security spokesman Patrick Mercer, who will introduce legislation within weeks to protect householders who use all but "grossly disproportionate" force to fight off intruders. Mr Mercer will introduce the law after topping the ballot for private members' Bills, guaranteeing that he will get parliamentary time for the measure, although it is unlikely to get on the statute books.