Chalk one up for the drug companies. In a hotly contested decision, the Supreme Court yesterday ruled in Pliva, Inc. v. Mensing that generic drug companies are immune from consumer lawsuits alleging misleading product labeling.

In a 5-4 decision, Justice Clarence Thomas delivered the Court’s opinion, stating that inadequate labeling suits against generic drug makers are pre-empted by federal drug regulations. Yesterday’s ruling, however, deviates from Wyeth v. Levine, a 2009 case in which the Court decided that FDA regulations cannot protect brand-name pharmaceutical companies from being sued under state law for the same types of mislabeling issues.

Since the Wyeth ruling, generic drug companies have striven to distance themselves from the decision, arguing that they shouldn’t face the same sorts of labeling suits as their brand-name counterparts because they’re required by federal law to use the exact same drug labels as the branded companies, according to the Wall Street Journal.

Pliva originated with the consolidation of two cases regarding the plights of Gladys Mensing and Julie Demahy, who both were prescribed Reglan, a heartburn medication, in 2001 and 2002, respectively, but instead received generic metoclopramide from their pharmacists. After taking the drug as prescribed for several years, they each developed tardive dyskinesia, a hard-to-treat disorder resulting in involuntary, repetitive body movements. They eventually sued the generic drug manufacturers for failing to provide adequate warning labels about the long-term effects of their drug, alleging the manufacturers were liable under state tort law. The drug companies countered, saying that federal law pre-empted the state tort claims.

Justice Thomas determined that had the plaintiffs taken Reglan as prescribed, suffered the same side effects and then sued the brand-name drug manufacturer, the case wouldn’t have been pre-empted. However, he concedes that the Court’s decision likely “makes little sense” to Mensing and Demahy, and acknowledges the “unfortunate hand that federal drug regulation has dealt” them, and others similarly situated.

In an impassioned dissent, Justice Sonia Sotomayor penned that as a result of the Court’s decision, consumers will now be at the mercy of their pharmacists when filling a prescription with generic or brand-name drugs, and will have little recourse if affected by inadequate labeling.

“The Court gets one thing right: This outcome ‘makes little sense,’” she wrote.