Bayer won a legal victory in its fight to limit liability from claims that its Roundup weed killer causes cancer, as a U.S. appeals court on Thursday said federal law shields the German company from a lawsuit by a Pennsylvania landscaper.

A U.S. appeals court ruled in favor of Bayer-owned Monsanto in a lawsuit alleging the company failed to warn customers about the cancer risk of its Roundup weed killer.

The U.S. Court of Appeals for the Third Circuit ruled Thursday that a federal law pre-empts state court claims filed in Pennsylvania by the pesticide’s users that Bayer should have warned them about cancer risks.