Okay, we’re nerds. We love this kind of stuff — even if some of you might find it soporific. From a delightful piece by Jonathan Starble in the Legal Times:

As one of its final acts last term, the U.S. Supreme Court issued Kansas v. Marsh, a case involving the constitutionality of a state death-penalty statute. The 5-4 decision exposed the deep divide that exists among the nation’s intellectual elite regarding one of society’s most troubling issues — namely, whether the possessive form of a singular noun ending with the letter “s” requires an additional “s” after the apostrophe.

In his majority opinion in Marsh, Justice Thomas dispensed with the “‘s” at the end: “Kansas’ capital sentencing statute.” In contrast, Justice Souter retained the additional “s”: “Kansas’s capital sentencing statute provides…”
Sorry, Justice Thomas; we’re with Justice Souter on this one. We follow the rule of Strunk and White: “Form the possessive singular of nouns by adding ‘s.”
Justice Scalia “goes both ways.” Sometimes he uses the “‘s,” and other times he doesn’t. How to explain this apparent inconsistency? Starble theorizes:

Scalia appears to believe that most singular nouns ending in “s” still demand an additional “s” after the apostrophe. Thus, in his Marsh concurrence, Scalia repeatedly referred to the relevant law as Kansas’s statute. He similarly added an “s” to form the words Ramos’s and witness’s.

Yet in other parts of the opinion, Scalia added only an apostrophe to form the words Stevens’, Adams’ and Tibbs’. Based on this, it would seem that he believes the extra “s” should be omitted if the existing “s” is preceded by a hard consonant sound. So, whereas Thomas makes his “s” determination based strictly on spelling, Scalia appears to look beyond the spelling and examine pronunciation as well.

Oh Nino, we’re disappointed. We thought that you, of all the justices, would appreciate a clear and concise rule over needless complexity. Your middle-of-the-road, split-the-baby approach to the “‘s” controversy is so very “Sandra Day O’Connor.” And we know how you feel about her wishy-washy jurisprudence.
Here’s our favorite paragraph in the whole piece:

Is it fair to deprive a small minority of the population of the right to assert possession in the same manner as everyone else [by adding 's]? Whereas Souter would answer an unequivocal no, Thomas would likely point out that he has gone his whole life with only one “s.” Because it worked for him, no one else in a similar situation should receive any preferential treatment. People who happen to be born with names ending in “s” should pull themselves up by their own bootstraps and learn to go without the additional letter. After all, it builds character.

Gimme an ‘S’: The High Court’s Grammatical Divide [Legal Times via WSJ Law Blog]