The Abrogation doctrine is a doctrine of United States constitutional law which determines when and how the United States Congress may waive a state's sovereign immunity and subject the state to lawsuits to which the state has not consented (i.e., to "abrogate" state immunity to such suits).
The United States was initially conceived as a union of sovereign states - that is, each U.S. state would have the same level of control over its internal affairs as a country, except that a federal government would exist to govern external affairs such as foreign policy and diplomacy, and to regulate relationships between the states. One of the characteristics of sovereignty is the power of the state to control the jurisdiction of its own courts, and through that power to control the circumstances under which a private citizen is permitted file a lawsuit against the state.
Most of the powers delegated to Congress spring from Article One of the U.S. Constitution, and these powers cannot be used to abrogate state sovereign immunity. In 1793, the Supreme Court of the United States decided the case of Chisholm v. Georgia, 2 U.S. 419 (1793), holding that a state could be sued in a United States federal court by a citizen of another state. This ruling sparked a negative reaction from lawmakers and two years later Congress and the states expressed their will by passing the Eleventh Amendment to the U.S. Constitution. The Amendment expressly forbade citizens of one state from suing another state, but said nothing about citizens suing their own state.
Nearly a century later, in the 1890 case of Hans v. Louisiana, 134 U.S. 1 (1890), the Supreme Court of the United States held that the Eleventh Amendment in fact re-affirms that states posses sovereign immunity and are therefore immune from being sued in federal court without their consent, even if the lawsuit alleges a violation of a citizen's constitutional rights.
In 1976, the Supreme Court modified this doctrine in a unanimous decision written by then-Associate Justice William Rehnquist, Fitzpatrick v. Bitzer, 427 U.S. 445 (1976). The Court held that the U.S. Congress can authorize lawsuits seeking monetary damages against individual states when it acts pursuant to powers delegated to it by amendments subsequent to the Eleventh Amendment. This can be done pursuant to clauses such as §5 of the Fourteenth Amendment to the U.S. Constitution, which explicitly allows Congress to enforce its guarantees on the states and thus overrides Eleventh Amendment sovereign immunity.
Bitzer "continued the line of reasoning that Rehnquist had acknowledged in Fry v. United States ... that cases involving Congress’ authority under Section Five present different problems than cases involving Congress’ commerce clause authority."[1] The doctrine has since developed a number of nuances and limitations. In particular, later cases explained that the Court would not infer Congressional intent to abrogate sovereign immunity, but would only uphold abrogations where Congress has "unequivocally express[ed] its intention to abrogate the Eleventh Amendment bar to suits against states in federal court." In order to do this, Congress must "mak[e] its intention unmistakably clear in the language of the statute." Atascadero State Hospital v. Scanlon, 473 U.S. 234 (1985).
Another limitation that the courts have read into Congressional power to abrogate is the "congruence and proportionality" test, also called the Boerne test because it was first discussed in City of Boerne v. Flores, 521 U.S. 507 (1997). Because the Fourteenth Amendment allows Congress to take "appropriate" action to enforce rights, the Court has determined that such action must be congruent and proportional to the deprivation of the right that Congress is seeking to remedy. For an example of a case where an act of Congress failed the Boerne test, see Kimel v. Florida Board of Regents (holding that the Fourteenth Amendment gave Congress no authority to permit a state to be sued for age discrimination); for an example where an act passed the Boerne test, see Nevada Department of Human Resources v. Hibbs.