The Supreme Court ruled yesterday that a network of antiabortion protesters that shut down abortion clinics nationwide through sit-ins and human blockades during the 1980s and '90s could not be punished under the same federal laws used to fight organized crime.

In deciding that these groups and their leaders could not be treated like gangsters under the law, the court was not opening the door to a resumption of their campaign against clinics, which is barred under a separate federal law passed in 1994.

But at a time of large demonstrations against a possible war in Iraq, the ruling could help advocates of other causes by making it more difficult for the targets of sit-ins, aggressive pickets and other forms of civil disobedience to reach for the heavy hammer of federal law, legal analysts said.

By a vote of 8 to 1, the justices ruled that abortion rights supporters could not use the federal Racketeer-Influenced and Corrupt Organizations Act (RICO) to sue the Pro-Life Action Network, Operation Rescue and their leaders for their campaign against clinics. When the abortion rights supporters filed their lawsuit in 1986, RICO, which provided for treble damages and authorized a single federal judge to stop the protests nationwide, was the strongest legal weapon available.

The protests included some illegal conduct, such as physical assaults and damage to clinic property, but shutting off access to the clinics did not meet the legal definition of extortion, one of the offenses that must be alleged to support a RICO claim, Chief Justice William H. Rehnquist wrote in the opinion for the court.

"The decision removes a cloud that has been hanging over the pro-life movement for 15 years," said Jay Sekulow, chief counsel of the American Center for Law and Justice, which represented Operation Rescue. "The ruling clearly shuts the door on using RICO against the pro-life movement."

The decision eliminates a $250,000 damage award and a court-ordered nationwide protest ban against the antiabortion groups. But it does not open the door to a renewed campaign against abortion providers, because in 1994 Congress passed the Freedom of Access to Clinic Entrances Act (FACE), designed to stop aggressive clinic blockades.

"Essentially, the court found that civil disobedients are not extortionists and racketeers," said Jamin B. Raskin, a professor of law at American University's Washington College of Law. "Someone who commits civil disobedience has bargained for a charge of criminal trespass or disorderly conduct, but not for 20 years in prison as a federal felon."

Justice John Paul Stevens dissented from yesterday's ruling, calling it "a dramatic retreat" from federal courts' and prosecutors' view of the law that would benefit "professional criminals."

Justice Ruth Bader Ginsburg, in a brief concurring opinion joined by Justice Stephen G. Breyer, implied that her concerns about the growth of RICO beyond its original mob-fighting purpose were heightened in a case that, although not directly about the First Amendment, had implications for political protest.

With FACE now on the books, "the principal effect of a decision against [the antiabortion groups] would have been on other cases pursued under RICO," Ginsburg noted. She added that Solicitor General Theodore B. Olson, arguing in favor of the National Organization for Women's position on behalf of the U.S. government, had conceded that civil rights sit-ins of the 1960s could have been punishable under his interpretation of the law.

The antiabortion protesters were backed by a long list of groups, including the Southern Christian Leadership Conference and People for the Ethical Treatment of Animals -- which told the justices in a friend-of-the-court brief that anti-fur protesters have been sued under RICO for their actions outside a fur shop.

For all their implications for the passionate debates over abortion and free speech, the two cases decided jointly yesterday, Scheidler v. NOW, No. 01-1118, and Operation Rescue v. NOW, No. 01-1119, basically hinged on the interpretation of a criminal statute.

Specifically, the court had to decide the meaning of the word "extortion" as it is used in the Hobbs Act, a 1946 statute designed to prevent gangsters from shaking down truckers in interstate commerce.

Committing extortion in violation of the Hobbs Act is one of the RICO offenses of which NOW and two abortion clinics specifically accused the antiabortion protesters when they sued them in an Illinois federal court in 1986. That offense is frequently the basis of RICO actions.

In 2001, the Chicago-based U.S. Court of Appeals for the 7th Circuit had ruled that the protesters had forcibly "obtained" property from the clinics, their doctors and patients -- in the intangible form of taking away their right to conduct business with one another.

But in yesterday's ruling, Rehnquist wrote that, although the precise contours of extortion under the Hobbs Act remain to be defined, "the effort to characterize [the protesters'] actions here as an 'obtaining of property' from [the clinics] is well beyond them. Such a result would be an unwarranted expansion of the meaning of the phrase."

"[E]ven when their acts of interference and disruption achieved their ultimate goal of 'shutting down' a clinic that performed abortions, such acts did not constitute extortion because petitioners did not 'obtain' . . . property," Rehnquist wrote. "[They] may have deprived or sought to deprive [the clinics] of their alleged property right of exclusive control of their business assets, but they did not acquire any such property."

For abortion rights groups, a RICO suit offered the advantage of going before a single court, instead of pursuing protesters on a series of state criminal and civil charges. But FACE also offers strong civil and criminal penalties, including jail time and punitive damages.

"Those types of mass civil disobedience are a thing of the past," said Thomas Brejcha, a lawyer for protest leader Joseph Scheidler. "FACE put an end to them."

The Rev. Rob Schenck, center, with the Rev. Patrick Mahoney, left, and Rock for Life Director Bryan Kemper, talks to reporters after the Supreme Court's decision.