Both Gladys Mensing and Julie Demahy developed Tardive Dyskinesia after taking a generic form of Reglan, as prescribed, for several years. The two brought suit against the generic drug manufacturers that produced the metroclopramide, alleging the companies failed to provide adequate warning labels under State tort law. Specifically, they alleged that the manufacturers knew or should have known that their labels did not adequately warn of the risk of Tardive Dyskinesia inherent in long term use of the product.

The manufacturers argued that FDA regulations require them to mimic the safety and efficiency labeling of their brand name counterparts, making it impossible to also comply with State tort law. Justice Thomas, writing for the Court, agreed with the drug manufacturers. The Court determined that Minnesota and Louisiana State laws hold drug manufacturers responsible for warning of danger and providing instructions for safe use of a product, while Federal law only requires generic drug manufacturers to “show that the safety and efficacy label proposed … is the same as the labeling for the brand name drug.” 21 U.S.C. §335 (j)(2)(A)(v).

Mensing and Demahy argued that generic manufacturers can comply with both Federal and State laws by changing their labels after FDA approval. First, they argued that the FDA’s “changes-being-effected” process allows manufacturers to comply with both laws. In Wyeth v. Levine, 555 U.S. 555 (2009), the Court found that Federal law did not pre-empt State law failure to warn claims against brand name drug makers because the FDA’s changes-being-effected process allows brand name manufacturers to strengthen their warnings without FDA pre-approval. In this case, however, the FDA told the Court that the process did not apply to generic drug manufacturers because it would violate the requirement that a generic drug label matches its brand name counterpart. The Court deferred to the FDA’s interpretation of its regulations.

Mensing and Demahy also argued that the manufacturers could have sent additional warnings, called “Dear Doctor letters,” to prescribing physicians. The FDA argued that this would have qualified as labeling, and it may have misled physicians into believing a difference between the brand name and the generic form existed. These actions would violate FDA regulations. The Court again deferred to the FDA’s interpretation of its regulations.

The FDA also told the Court that generic drug manufacturers do have a duty to request that the FDA strengthen a drug’s label. The manufacturers disagreed. The Court did not have to resolve this issue because it found that even if the manufacturers would have asked the FDA for assistance, they would not have satisfied the State law requirements. This is because the State law required safer labels, not an attempt to obtain safer labels. Justice Thomas reasoned that if requesting a change in the law satisfied stricter State laws, Federal and State laws would rarely conflict because a third party could always lobby for a change in the current Federal law.

For the foregoing reasons, Justice Thomas found that generic drug manufacturers could not comply with both State law and Federal requirements. He further explained that because the U.S. Constitution’s Supremacy Clause established that Federal law “shall be the supreme Law of the Land,” U.S. Const. art. VI, cl. 2, a Federal law pre-empts State law. In turn, FDA regulations, authorized by Federal law, pre-empt Mensing and Demahy’s State law failure to warn claims.