The Supreme Court declined on Monday to hear a bid by a group of physicians and health care providers to revive their antitrust lawsuit accusing drugmaker Merck of misleading federal regulators to maintain a decadeslong monopoly over the mumps vaccine market.

The justices turned away an appeal by the plaintiffs of a lower court's decision to throw out the lawsuit on the basis that the drugmaker was protected under a legal doctrine that immunizes companies from antitrust claims based on actions aimed at swaying government decision-making.

A collection of family doctors and other physicians from New Jersey and New York filed the lawsuit in 2012 in federal court in Philadelphia, seeking monetary damages.

The claims remaining in the long-running litigation involve allegations that the plaintiffs were overcharged for New Jersey-based Merck's mumps vaccines as a result of the company's monopolization of that market in violation of federal antitrust law and New Jersey and New York state laws.

The plaintiffs said submissions by Merck to the Food and Drug Administration contained misrepresentations that effectively boxed out competitors such as GlaxoSmithKline and delayed market entry of a rival vaccine for more than a decade.

Merck made the only mumps vaccine in America from 1967 until 2022. It is sold as part of a combined vaccine against mumps, measles, and rubella, known as MMR-II.

The FDA in the 1990s raised concerns that the mumps vaccine lost potency toward the end of its 24-month shelf life, according to the lawsuit.

The lawsuit accused Merck of misleading the FDA in the 2000s about the potency and efficacy of the mumps vaccine. Merck boosted the vaccine's initial potency and submitted a supplemental application to the FDA to continue selling it without revising its efficacy claims.