Columbia, SC (WLTX) - SCE&G is suing over a new law that's designed to lower power bills for customers that were being charged for a failed nuclear reactor project.

The utility filed the lawsuit Monday in federal court, claiming that the measure passed last week by the South Carolina legislature is unconstitutional.

The new law primarily gives SCE&G customers an experimental 15 percent reduction in the costs they were paying for the abandoned construction of two nuclear reactors at the V.C. Summer Nuclear station in Fairfield County. Up until now, roughly 18 percent of every customer's bill has gone to the project.

South Carolina Governor Henry McMaster had vetoed the bill, saying customers should be given the full 18 percent rate reduction. Lawmakers overrode that veto, and the bill immediately went into effect.

SCE&G says the rate reduction and other parts of the law are an unlawful taking of private property, denies them due process of law, and constitutes an unlawful bill of attainder.

SCANA/SCE&G was able to bill customers for the project because of a law passed by South Carolina lawmakers in 2007 called the Base Load Review Act. It let utilities go ahead and charge customers for construction of projects before and during their construction.

In the wake of the V.C. Summer fiasco, lawmakers called for the repeal of the law, and they did just that during a vote Wednesday in the House and Senate.

State run utility Santee Cooper was also part of the failed project, but SCANA had the majority stake. Both of them walked away from the plan a year ago, after years of construction and billions of dollars spent. That decision also cost 5,600 people their jobs.

The reactors were supposed to have provided another source of energy to meet rising demand from the growing number of users in South Carolina.

Another key part of the law approved by the House and Senate is giving subpeona power to the Office of Regulatory Staff, a state agency that has some authority over utilities. The bill allows them to get their hands on secret documents by power companies.

The General Assembly had used a conference committee--a special group of three lawmakers from the House, three from the Senate-- to get a deal done and iron out differences between competing versions of their proposals.

Virginia-based Dominion Energy, which is attempting to buy SCE&G, said the legislature's action put in peril a plan they have which would give all customers $1,000 and a 7 percent rate reduction due to the V.C. Summer failure.