Allen v. Cooper is an excellent opinion for teaching Sovereign Immunity

Justice Kagan pithily summarized Boerne, Florida Prepaid, and Kimel

The "congruent and proportional" test is one of the toughest doctrines to teach in constitutional law. The interplay between Boerne v. Flores, Florida Prepaid, and Kimmel is complicated and gives students difficulties. I would highly recommend Allen v. Cooper as a good teaching case. Justice Kagan's majority opinion is tight, and pithily summarizes all of the leading doctrines.

Consider these paragraphs:

For an abrogation statute to be "appropriate" under Section 5, it must be tailored to "remedy or prevent" conduct infringing the Fourteenth Amendment's substantive prohibitions. City of Boerne v. Flores (1997). Congress can permit suits against States for actual violations of the rights guaranteed in Section 1. And to deter those violations, it can allow suits against States for "a somewhat broader swath of conduct," including acts constitutional in themselves. Kimel. But Congress cannot use its "power to enforce" the Fourteenth Amendment to alter what that Amendment bars. Kimel (prohibiting Congress from "substantively redefin[ing]" the Fourteenth Amendment's requirements). That means a congressional abrogation is valid under Section 5 only if it sufficiently connects to conduct courts have held Section 1 to proscribe.

To decide whether a law passes muster, this Court has framed a type of means-end test. For Congress's action to fall within its Section 5 authority, we have said, "[t]here must be a congruence and proportionality between the injury to be prevented or remedied and the means adopted to that end." Boerne. On the one hand, courts are to consider the constitutional problem Congress faced—both the nature and the extent of state conduct violating the Fourteenth Amendment. That assessment usually (though not inevitably) focuses on the legislative record, which shows the evidence Congress had before it of a constitutional wrong. See Florida Prepaid. On the other hand, courts are to examine the scope of the response Congress chose to address that injury. Here, a critical question is how far, and for what reasons, Congress has gone beyond redressing actual constitutional violations. Hard problems often require forceful responses and, as noted above, Section 5 allows Congress to "enact[] reasonably prophylactic legislation" to deter constitutional harm. Kimel; Boerne (Congress's conclusions on that score are "entitled to much deference"). But "[s]trong measures appropriate to address one harm may be an unwarranted response to another, lesser one." Boerne. Always, what Congress has done must be in keeping with the Fourteenth Amendment rules it has the power to "enforce."

Perfect.

And, I commend Justice Kagan for resisting any pirate puns, until the penultimate page of the majority. And it was a gem:

Congress acted before this Court created the "congruence and proportionality" test. For that reason, Congress likely did not appreciate the importance of linking the scope of its abrogation to the redress or prevention of unconstitutional injuries—and of creating a legislative record to back up that connection. But going forward, Congress will know those rules. And under them, if it detects violations of due process, then it may enact a proportionate response. That kind of tailored statute can effectively stop States from behaving as copyright pirates. Even while respecting constitutional limits, it can bring digital Blackbeards to justice.

Alas, Justice Breyer's pirate reference falls flat.

One might therefore expect that someone injured by a State's violation of that duty could "resort to the laws of his country for a remedy," ibid., especially where, as here, Congress has sought to provide one. Or more concretely, one might think that Walt Disney Pictures could sue a State (or anyone else) for hosting an unlicensed screening of the studio's 2003 blockbuster film, Pirates of the Caribbean (or any one of its many sequels).

Arr.