The court also ruled that the legislature must redraw the districts in time for the fall elections.
The justices decided the districts were unconstitutional since counties were unnecessarily divided and the Democrat-controlled legislature had violated restrictions designed to prevent tipping electoral districts in favor of incumbents.
After the new districting plan was announced last fall, Republicans and others filed suit against the state, claiming the Democrats had redrawn the districts to violate the constitution for their own benefit.
Johnston County Superior Court Judge Knox Jenkins ruled in favor of the Republicans, but immediately blocked his own ruling, deferring to the state's highest court to decide an appropriate course of action.
Under the old districts, 60 percent of Democratic state representatives and senators would have run unopposed.
The courts ruled that Democrats had intentionally isolated key Republican legislators by dividing districts in ways to put them in competition with strong Democrats in traditionally Democratic regions.
Electoral districts are redrawn every ten years based on U.S. Census returns. The new districts are supposed to reflect demographic changes in the state.
Any redistricting plan would have to be approved by the U.S. Justice Department before the state could set a primary date.
The legislature will have to meet through committee or in special session to redraw the maps. Gov. Mike Easley has not announced when or if he will call for a special session.
Each step-setting the district lines, submitting a plan to the Justice Department, and finalizing an election date upon approval by Justice-requires as much as 60 days. Generally it takes much less.
Bladen County Elections Supervisor Larry Hammond said the court's decision hasn't changed things locally. Election supervisors are still waiting to her when a date will be set.
"As of Thursday," he said, "we have received no direction from the state board of elections as to when a primary may be scheduled.
Officials have speculated that the statewide primary date will likely be held in September, but no firm date has been set.