[2] Section 5 of the Judiciary Act of 1793 provided that no "writ of injunction [shall] be granted to stay proceedings of any court of a state.
dead.”[17] The modern era of Anti-Injunction Act doctrine began in 1941, when the Supreme Court decided Toucey v. New York Life Insurance Co.[18] The case began when New York Life prevailed in federal court on Toucey's claim to collect monthly disability insurance payments.
Toucey then assigned his benefits to another individual, who sued New York Life in state court on functionally the same claim.
The Supreme Court, in a majority opinion by Justice Felix Frankfurter, held that the injunction was inappropriate because the Relitigation Exception "patently violates the expressed prohibition of Congress.
[22] The 1948 Act's legislative history states its purpose as "restor[ing] the basic law as generally understood and interpreted prior to the Toucey decision.
"[25] The modern Supreme Court has affirmed Toucey’s understanding that the Act is rooted in notions of comity and federalism.
"[42] The theory behind the exception is that, by expressly allowing stays of state court proceedings pursuant to certain statutes, Congress validly overrides the limitation that it imposed in the Anti-Injunction Act.
"[63] Despite the exception's seemingly permissive language, however, the Supreme Court has reiterated that it does not extend to in personam actions (i.e. cases not dealing with real property).
[64] In Atlantic Coast Line Railroad Co. v. Brotherhood of Locomotive Engineers,[65] Justice Hugo Black's majority opinion held that the exception does not apply simply because there is duplicative litigation in state and federal courts, even if the federal court has exclusive subject matter jurisdiction.
[75] For instance, under so-called Pullman abstention, a federal court will generally abstain from deciding a case presenting unresolved state-law and federal constitutional questions if a state court could clarify the state-law question to make the constitutional ruling unnecessary.
[76] Under Younger abstention, a federal court will generally abstain from interfering with ongoing state criminal proceedings.
[79] Like the Anti-Injunction Act, Pullman, Younger, Burford, and Thibodaux abstention are rooted in principles of federalism.
For that reason, they have been prominently criticized as "judicial usurpation[s] of legislative authority in violation of separate of powers.