Direct Rule is the term given to the running of the day-to-day administration of Northern Ireland directly from Westminster. It was official British policy from the suspension of Stormont in March 1972, until the establishment of the Northern Ireland Assembly under the terms of the Good Friday Agreement in 1998.
Since the Good Friday Agreement, the Assembly has been suspended (and thus Direct Rule re-imposed) on at least three occasions, 1999, 2001 and at the time of writing (2004), the Assembly remains suspended for the indefinite future.
The implementation of Direct Rule is the prerogative of the Secretary of State for Northern Ireland who decides if and when to do so.
