As I indicated the other day, I find grotesque the possessive form of “Congress” that Justice Ginsburg used in her recent dissent—“Today’s decision returns the ball to Congress’ court”—at the same time that I recognize that that form is, alas, common.
I’m pleased to note that Bryan Garner (co-author, with Justice Scalia, of The Art of Persuading Justices) has this strong statement on the issue in his excellent Dictionary of Modern Legal Usage: “The best practice, advocated by Strunk and White in The Elements of Style and by every other authority of superior standing, is to add –’s to all singular possessives, hence witness’s, … Congress’s.” (Garner posits two exceptions to this rule, neither applicable—and both, in my judgment, dubious.)
A trusty research assistant and I have attempted to discern the practice of the nine justices on forming the singular possessive of “Congress” and “witness”. That task is complicated by the fact that the common search engines seem designed to ignore apostrophes. But our tentative conclusion is that three justices—Roberts, Scalia and Souter—have the right practice. (I’m finally able to say something positive about Souter!). The other six, it appears, consistently don’t.
Interestingly (at least if you find any of this interesting), the Harvard Law Review appears to have vacillated between the two forms, getting it wrong for some period before 1962, from 1968 to 1984 (with some exceptions), and from 1988 to 1991, and getting it right from 1962 to 1968, 1984 to 1987, and from 1991 to the present. (I don’t have a specific memory of the matter, but it wouldn’t surprise me if I had some minor role in fixing things in 1984.)
Update: I’ve just run across this excellent 2006 essay—“Gimme an ‘S’: The High Court’s Grammatical Divide”—by West Hartford attorney Jonathan M. Starble on how the Court’s ruling in Kansas v. Marsh exposed a deep divide over the singular possessive. Starble’s more extensive research indicates that Scalia has been inconsistent in forming the possessive of “Congress” and, more broadly, that Scalia appears to adopt a pronunciation rule (that is, use the apostrophe and the “s” when the possessive form changes the pronunciation) rather than the Garner rule. He also puts Roberts on the unsound side of the divide, though he doesn’t spell out his evidence for doing so.