Lincoln, Neb. --  A Nebraska judge on Wednesday struck down a law that allowed the Keystone XL oil pipeline to proceed through the state, a victory for opponents who have tried to block the project.

Lancaster County Judge Stephanie Stacy issued a ruling that invalidated Nebraska Gov. Dave Heineman's approval of the route. Stacy agreed with opponents' arguments that law passed in 2011 improperly delegated the decision-making power to Heineman to give the company eminent domain powers within the state. Stacy said the decision should have been made by the Nebraska Public Service Commission, which regulates pipelines and other utilities.

The lawsuit was filed by three Nebraska landowners who oppose the pipeline.

"Under the Court's ruling, TransCanada has no approved route in Nebraska," Dave Domina, the landowners' attorney, said in a statement. "TransCanada is not authorized to condemn the property against Nebraska landowners. The pipeline project is at standstill in this state."

Domina said the ruling means that the governor's office has no role to play in the pipeline, and decisions within the state must be made by the Public Service Commission. The decision on a federal permit still rests with President Barack Obama.

The ruling could cause more delays in finishing the pipeline, which would carry oil from Canada to Texas refineries.

Phone messages left with pipeline developer TransCanada were not immediately returned Wednesday afternoon.