The Competitive Enterprise Institute has filed a lawsuit; S&M Brands v. Caldwell with the Supreme Court to break the MSA because it is unconstitutional. The Constitution’s Compact Clause mandates that “No State shall, without the Consent of Congress … enter into any Agreement or Compact with another State."
"The Compact Clause is not the only legal provision violated by the tobacco deal. Professors of antitrust law say it also violates the antitrust laws, since the unwritten exception in the antitrust laws for state-enforced cartels has never been extended by the Supreme Court to interstate cartels like the tobacco deal. (The Supreme Court has said that the unwritten exception in the antitrust laws for government-backed cartels is narrowly construed to cover only some government-backed cartels, and only covers cartels imposed by a state, not municipalities or other entities that lack Eleventh Amendment immunity.)