WASHINGTON  In a major setback for business groups that had hoped to build a barrier against injury lawsuits seeking billions of dollars, the Supreme Court on Wednesday said state juries may award damages for harm from unsafe drugs even though their manufacturers had satisfied federal regulators.

The ruling could have significant implications beyond drug manufacturing. Many companies have sought tighter federal regulation in recent years in part to shield themselves from litigation.

The court, by a 6-to-3 vote, upheld a jury verdict of $6.7 million in favor of a musician from Vermont whose arm had to be amputated after she was injected with an antinausea drug. The drug’s manufacturer, Wyeth, had argued that its compliance with the Food and Drug Administration’s labeling requirements should immunize it from lawsuits.

Pharmaceutical companies were especially disappointed by Wednesday’s decision.

Ronald Rogers, a spokesman for Merck, said, “We believe state courts should not be second-guessing the doctors and scientists at the F.D.A.”