The U.S. Supreme Court explained in the hoary case of Hansberry v. Lee, 311 U.S. 32, 40–41 (1940),
It is a principle of general application in Anglo-American jurisprudence that one is not bound by a judgment in personam in a litigation in which he is not designated a party . . . A judgment rendered in such circumstances is not entitled to the full faith and credit which the Constitution and statute of the United States prescribe, and judicial action enforcing it against the person or property of the absent party is not that due process which the Fifth and Fourteenth Amendments requires.
This is black letter constitutional law, which is taught to virtually every first-year law student in the country. Somehow, however, the Environmental Protection Agency (EPA) and the Department of Justice (DOJ) have been urging the federal courts to approve settlements under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), which may violate this principle.