Federal law prevents people injured by generic drugs from suing generic drugmakers. But recent court rulings may allow generic drug users to sue makers of the brand-name versions.

The rulings apply to people harmed by generic drugs in Massachusetts and California. Brand-name drugmakers may be liable for injuries caused by generic drugs they did not manufacture or sell.

Generic drugs can cause the same side effects as the brand-name drugs they’re copying. Generic drugs must carry the same label as the brand-name versions. Only makers of brand-name drugs may add warnings to drug labels without approval from the U.S. Food and Drug Administration.

The U.S. Supreme Court says courts may not order generic drugmakers to violate the law by changing their labels. So, federal law bars lawsuits that accuse generic drugmakers of failing to warn of dangerous side effects. This is called preemption.

But two state supreme courts said brand-name drugmakers may be responsible for problems caused by generic drug labels. They ruled to allow people harmed by generic drugs in the two states to sue the brand-name companies.

The latest ruling came March 16, 2018, from the Massachusetts Supreme Court. The case involved a generic version of Merck’s drug Proscar.

The court ruled patients who take generics may sue brand-name drugmakers when they intentionally fail to warn of dangers. Patients can also sue if a maker of a brand-name drug fails to warn when it should have known of serious danger. Lawsuits can’t just claim negligence, a lesser standard, the court said.

The decision comes months after a California Supreme Court ruling. The California case involved a Novartis drug Brethine.

The court said California lawsuits could sue brand-name drugmakers when they are negligent. This means it’s easier for patients injured by generics to sue in California.