It is an aspect of the traditional view of Parliamentary sovereignty that the courts will not rule as invalid an Act of Parliament, or any part of an Act, which has been passed in the correct fashion. This view has been questioned by some, including some senior judges. They argue that certain limits on the legislative competence of Parliament are necessary to protect those fundamental values that are essential in a democracy. Many who argue for limits to the legislative competence of Parliament also suggest that the relationship between the different arms of the government is one based on mutual respect, restraint and co-operation. If Parliament legislates in such a way as to breach this mutuality, and in a way that will cause conflict between Parliament and the courts, then, it is suggested, the courts may reply in kind by holding that legislation, or part of it, invalid. It is argued here that in the recent quarrel between the Government and the courts over the ouster clause contained in the Asylum and Immigration (Treatment of Claimants, etc.) Bill 2003, the Government was encouraged to undertake to amend the legislation as a result, at least in part, of intimations by senior judges that the clause could be overruled by the courts. This demonstrates, it is argued, that both sides believed this threat to have some force.