The good news: In retrospect, they now have come to the realization that it might be a wee bit unconstitutional.
The bad news: They may be wrong.
Proving that all idiotic history repeats itself, there are two major Supreme Court cases dealing with castration. The first is Buck v. Bell (274 U.S. 200 (1927)), perhaps Justice Oliver Wendell Holmes Jr.'s most infamous opinion, where he upheld Virginia's castration program for the feeble minded with the pithy "three generations of idiots are enough."
The second case was Skinner v. Oklahoma (316 U.S. 535 (1942)) In that case, the court overturned Oklahoma's castration law. However, it did so (and here's where it gets interesting) without overturning Bell. The ruling instead emphasis the Equal Protection deficiencies in Oklahoma's law:
Sterilization of those who have thrice committed grand larceny with immunity for those who are embezzlers is a clear, pointed, unmistakable discrimination. Oklahoma makes no attempt to say that he who commits larceny by trespass or trick or fraud has biologically inheritable traits which he who commits embezzlement lacks. Oklahoma's line between larceny by fraud and embezzlement is determined, as we have noted, 'with reference to the time when the fraudulent intent to convert the property to the taker's own use' arises. We have not the slightest basis for inferring that that line has any significance in eugenics nor that the inheritability of criminal traits follows the neat legal distinctions which the law has marked between those two offenses. In terms of fines and imprisonment the crimes of larceny and embezzlement rate the same under the Oklahoma code. Only when it comes to sterilization are the pains and penalties of the law different. The equal protection clause would indeed be a formula of empty words if such conspicuously artificial lines could be drawn. (316 U.S. at 541-42) (citations omitted)
In other words, the Court struck down the law because it irrationally distinguished between such crimes as Larceny and Embezzlement, one being punishable by castration, the other not. The court also noted that since castration obviously affected a fundamental right, "strict scrutiny" was the appropriate standard (Id., at 541). However, after Skinner, the eugenics movement began to fade, and no state was stupid enough to reenact a castration law (until now).
The question is, then, would a state law that mandated castration for sex offenders pass strict scrutiny (assuming Bell is still good law and castration is not per se unconstitutional)? I think one could make a compelling argument that it does. Sex offenders are a particular class of offenders whose "weapon," so to speak, is their genitalia and sex drive. The state could plausibly argue that depriving offenders of that "weapon" is no different than depriving felons of their right to bear arms. Indeed, in a sense the argument would make more sense in this case, since, to borrow from Frank Easterbrook, this compares "the right to bear arms, which is in the constitution, to the right to one's penis, which is not." There is, I believe, quite a bit of evidence that suggests that castration reduces the sex drive of human beings (no surprise there) and thus would be a valid hedge against recidivism. Ultimately, I think this is an argument that could be made.
I do not think that castration is sound policy, and think that Bell should be overturned. But as the jurisprudence stands now, I do not think Alabama's law is unconstitutional.
Would that I could agree with them this time.
A Public Defender and PrawfsBlawg have more, and thanks to Objective Justice's BlawgReview for the original tip.