The Supreme Court on Monday issued a ruling that makes it more difficult for plaintiffs attorneys to look for friendly locations for their lawsuits, a practice known as “court shopping.”

The court reversed a lower-court decision on class-action lawsuits, ruling that hundreds of defendants who sued Bristol-Myers Squibb in California over injuries associated with the blood-thinning drug Plavix could not sue in that state because they were not residents.

The 8-to-1 decision led by Justice Samuel A. Alito Jr. rejects a liberal standard for where plaintiffs can sue, creating a hurdle for litigants. The majority decision said that non-state plaintiffs had failed to establish a strong connection between their alleged injury and Bristol-Myers actions in California.

The plaintiffs had claimed that the drug manufacturer misrepresented the risks of strokes and heart attacks related to Plavix.

The court’s ruling reversed a judgment by the California Supreme Court, essentially directing the dismissal of the 592 non-California claims from 33 other states. There are 86 claims against the pharmaceuticals company from California.

The court, speaking specifically of the non-California residents who joined the class-action suit against the drugmaker, said those individuals “are not California residents and do not claim to have suffered harm in that State. . . . It follows that the California courts cannot claim specific jurisdiction.”

“The non-residents were not prescribed Plavix in California, did not purchase Plavix in California, did not ingest Plavix in California, and were not injured by Plavix in California,” Alito said in his majority opinion. “The mere fact that other plaintiffs were prescribed, obtained, and ingested Plavix in California — and allegedly sustained the same injuries as did the non-residents — does not allow the state to assert specific jurisdiction over the nonresidents’ claims.”

In her dissent, Justice Sonia Sotomayor said she feared the consequences of Monday’s decision.

“The majority’s rule will make it difficult to aggregate the claims of plaintiffs across the country whose claims may be worth little alone,” she said in the dissent. “It will make it impossible to bring a nationwide mass action in state court against defendants who are ‘at home’ in different States. And it will result in piecemeal litigation and the bifurcation of claims. None of this is necessary.”

Andrew Pincus, a Supreme Court lawyer with the Washington office of Mayer Brown, said the ruling leaves open “two big questions:”

“How much of a connection does there have to be between the claim and the place the lawsuit is filed? Secondly, will today’s ruling mean that class action will only be filed in a court that can assert jurisdiction over every single class member?”