The justices questioned the size of the zone and whether the state could find less restrictive ways of ensuring patient access and safety.

No one has been prosecuted under the 2007 law, which state officials and clinic employees have said has resulted in less congestion outside the clinics.

The court — which bars protests on its plaza, but allows them on the public sidewalks — last considered abortion clinic protest zones in 2000, when it upheld a Colorado law.

It seemed possible that there could be more than the five votes needed to strike down the law after Justice Elena Kagan said she was “hung up” over the size of the zone.

But it was hard to tell whether the court might also upend its 2000 ruling in support of the Colorado zone, which has been criticized by free speech advocates for unfairly restricting protesters’ rights.

That’s because Chief Justice John Roberts, normally an active questioner, did not ask a single question of any of the three lawyers who argued the case.

Painted semicircles outside Planned Parenthood clinics in Boston, Springfield and Worcester mark the spot beyond which abortion opponents are free to protest and try to persuade women not to end their pregnancies. Inside the line, protesters and supporters alike risk arrest.

The justices tried different comparisons in imagining the size of the zone. Kagan compared it to the width of the courtroom, which is 82 feet by 91 feet. Justice Sonia Sotomayor suggested two car lengths, which is roughly equivalent to the distance from the start of the zone to the building line at the Boston clinic, which has a recessed entrance.

Obama administration lawyer Ian Gershengorn compared the protest-free zone to the NBA’s three-point line, 22 feet at its shortest point to the basket.

Eleanor McCullen, 77, and other protesters at those clinics sued the state over its 2007 law setting up the buffer zone, saying it limits their ability to encounter patients arriving for care. Federal courts in Massachusetts have upheld the law as a reasonable imposition on protesters’ rights.

Mark Rienzi, representing the protesters, said the state could deal with congestion problems by asking people to move, “not dragging Mrs. McCullen off to prison.” McCullen attended Wednesday’s session as did Marty Walz, the sponsor of the 2007 law in the Massachusetts House of Representatives and now the president and CEO of the Planned Parenthood League of Massachusetts.

Lawyers for Massachusetts and the Obama administration defended the law as a reasonable effort that still allows people to attempt to persuade women arriving at the clinics not to have abortions.

State officials and clinic employees say patients and staff feel safer and find it easier to enter the clinics. Abortion rights groups report that incidents of violence are down in states and cities that have buffer zones. The last serious violence in Massachusetts was in 1994, when a gunman killed two employees at two clinics in the Boston area.

In 2000, the Supreme Court voted 6-3 to uphold a different buffer zone in Colorado in a decision that some free-speech advocates, who also support abortion rights, have criticized.

Since then, four of the six justices in the majority have retired, while the three dissenters — Justices Anthony Kennedy, Antonin Scalia and Clarence Thomas, remain on the court. Thomas was silent Wednesday, as is his custom during arguments, while Kennedy and Scalia made clear their problems with the Massachusetts law.

Scalia objected even to calling McCullen and the others who challenged the law protesters. “This is not a protest case. They don’t want to protest. They want to talk to women and talk them out of abortions,” he said.

Kennedy questioned whether other state and federal laws could not be used to accomplish the same goal of keeping access to the clinics open. “What’s wrong with the physical obstruction statutes as an answer to the problems Massachusetts is facing?” Kennedy said.

Two of the four newer justices since 2000 are Roberts and Justice Samuel Alito, who both have voted to restrict abortion rights. Roberts also has written strong opinions in favor of protesters’ rights, including members of a Kansas church who protest outside military funerals. Alito has been more willing to limit those rights.

But Alito appeared certain to vote to strike down the law, which he said treats people differently based on their point of view.

Assistant Attorney General Jennifer Grace Miller of Massachusetts failed to dissuade Alito that the issue was not what anyone was saying, but the state’s desire to keep traffic moving in front of the clinic.

Before the case was argued, state Attorney General Martha Coakley said the current case should come out the same way as the Colorado case did 14 years earlier. The only thing that has changed, Coakley said, is the makeup of the court.

“The state has a huge interest in making sure that everybody is safe and that all rights are protected,” she said. The Obama administration warned that limits on conduct near funerals, courthouses, polling places, homes and airports could be called into question if the court strikes down the law.

Massachusetts had a “floating buffer zone” law modeled on the Colorado law that was designed to keep protesters and patients apart. But Coakley said it was confusing and hard to enforce, prompting the state to adopt a fixed, 35-foot zone.

Notre Dame law professor Richard Garnett, who filed a brief in the case on the protesters’ side, said the Massachusetts law is even more restrictive than the Colorado law. Garnett said the court should have struck down the Colorado law, despite “the temptation to silence unwelcome expression.”

Garnett said free speech, not the right to an abortion, is at issue in the new case. The AFL-CIO, concerned about limits on picketing, also is calling for the law to be struck down.

WATCH

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