“The big one.” “A major victory.” “A game changer.” That's how many lawyers in the defense bar described Monday's landmark decision by the U.S. Supreme Court in Bristol-Myers Squibb v. Superior Court of California.

They're not too far off. In mere hours, a judge in Missouri ended a pivotal trial over Johnson & Johnson's baby powder because of the court's decision, granting a mistrial in a courtroom in St. Louis, a venue favored by many plaintiffs.

Even plaintiffs lawyers concede that Bristol-Myers took a hatchet to a lucrative growth area in mass torts: Lawsuits brought on behalf of dozens of individuals in venues considered more favorable to plaintiffs, such as certain state courts in California, Illinois, Missouri and Texas. The court held that plaintiffs in such a case against Bristol-Myers Squibb Co. — referred to as a “mass action” — had failed to establish specific jurisdiction because there wasn't enough of a link between their claims and California, where they brought their lawsuit. The ruling, like many of the Supreme Court's prior decisions on jurisdictional matters, tightened the rules on where corporate defendants can be sued.