Comity is the deference paid by the institutions of one government to the acts of another government—not out of compulsion, but in the interest of cooperation, reciprocity, and the stability that grows out of the satisfaction of mutual expectations. When the courts of one nation give effect to foreign laws and the orders of foreign courts, that deference is called judicial comity. (See act of state doctrine.)
The states of the United States are, for many purposes, separate sovereignties. A state court, in deciding a case, starts from the assumption that it will apply its own state law. When it applies the law of another state, normally it does so as a matter of comity. (See choice of law.) Because comity is not so much a rule as an attitude of accommodation, state courts generally feel free to refuse to apply a law that violates their own state's public policy. In Nevada v. Hall (1979) California courts upheld a million-dollar verdict against the State of Nevada in an automobile injury case, rejecting Nevada's claim of sovereign immunity; the Supreme Court affirmed, saying that the Constitution left to California's courts the degree of comity they should afford to Nevada law.
A state court's enforcement of the valid judgment of a court of another state is not merely a matter of comity but is required by the full faith and credit clause. Similarly, the supremacy clause binds state courts to enforce valid federal laws and regulations, along with the valid judgments of federal courts.
Notions of comity have recently taken on increased significance in the federal courts themselves. A federal court may, under some circumstances, stay its proceedings because another action between the same parties is pending in a state court. The Supreme Court in Fair Assessment of Real Estate Association v. McNary (1981) discovered in the Tax Injunction Act (1937) a general principle of comity forbidding federal courts not only to enjoin the collection of state taxes but also to award damages in state tax cases. And comity has been a major consideration in the development of the "equitable restraint" doctrine of younger v. harris (1971), which generally forbids a federal court to grant an injunction against the continuation of a pending state criminal prosecution.
Kenneth L. Karst
(see also: Abstention Doctrine.)