Planning enforcement is one of the most diverse and complex areas of law. It is primarily concerned with the taking of steps against development carried on without planning permission or in breach of conditions on a planning permission. These powers are principally contained in Part VII of the Town and Country Planning Act 1990. They were heavily amended by the Planning and Compensation Act 1991. Subsequent amendments have been made in the Planning and Compulsory Purchase Act 2004 (introducing temporary stop notices) and the Localism Act 2011 (dealing with time limits and advertising enforcement).