The court's 8-1 ruling applies to protests of all sorts, not just at abortion clinics, the Associated Press said. The decision lifts a nationwide injunction that barred people from interfering with abortion-clinic business.
Chief Justice William Rehnquist, writing for the majority, said that when protesters do not "obtain" property, they cannot be punished under federal extortion laws.
The ruling was a victory for Operation Rescue, pro-life leader Joseph Scheidler and others, news services said. They were sued by the National Organization for Women and others for tactics to block access to clinics.
The court's ruling is a victory for Operation Rescue, pro-life leader Joseph Scheidler and others who had been ordered to pay damages to abortion clinics and were barred from interfering with their businesses for 10 years. Today's ruling ends that injunction.
Numerous friend-of-the-court briefs had said that if abortion protests were labeled as extortion, then all protest would be imperiled, the Washington Times said in December.
The punishments against the pro-lifers were meted out under provisions of the 1970 Racketeer Influenced and Corrupt Organizations Act, known as RICO, and the Hobbs Act, a 1946 law aimed at crushing organized crime.