Kennedy also wasn’t sympathetic to treating married gay couples differently under federal law, charting out a compromise that lets states define marriage and requires the federal government to accept their definition.

Perhaps conscious of Kennedy’s predicament, Roberts tried to build consensus against striking down DOMA on federalism grounds, knowing that neither side arguing the case was seeking that middle path. He repeatedly — and successfully — asked the government’s anti-DOMA lawyer to affirm that it does not believe the 1996 law violates states rights.

“So just to be clear, you don’t think there is a federalism problem with what Congress has done in DOMA?” Roberts asked U.S. Solicitor General Donald Verrilli on Wednesday. “We — no, we don’t, Mr. Chief Justice,” Verrilli responded.

Lyle Denniston, a veteran Supreme Court analyst with the award-winning SCOTUSblog, described Roberts’ move as “a strategic effort to put Kennedy in a box.”

This is facile thinking in my view. What, pray tell, puts Justice Kennedy in a box? He is the deciding vote, even though he probably will not carry five votes for an opinion that decides solely on federalism grounds. (Unfortunately, I think it is too probable that a non-conservative Justice will join Justice Kennedy to give him cover if he asks for it. See Kagan and Breyer joining Chief Justice Roberts on his absurd reasoning on Medicaid expansion in the ACA case.)

ROBERTS, C. J., announced the judgment of the Court and delivered the opinion of the Court with respect to Parts I, II, and III–C, in which GINSBURG, BREYER, SOTOMAYOR, and KAGAN, JJ., joined; an opinion withrespect to Part IV, in which BREYER and KAGAN, JJ., joined; and an opinion with respect to Parts III–A, III–B, and III–D. GINSBURG, J., filed an opinion concurring in part, concurring in the judgment in part,and dissenting in part, in which SOTOMAYOR, J., joined, and in whichBREYER and KAGAN, JJ., joined as to Parts I, II, III, and IV. SCALIA, KENNEDY, THOMAS, and ALITO, JJ., filed a dissenting opinion. THOMAS, J., filed a dissenting opinion.

But there are no boxes for SCOTUS Justices. They can write alone if they wish. Indeed the unmistakable attack on the power of precedent is one of the least commented aspects of the Roberts Court. While rarely expressly overruling precedent, the Roberts Court is a champion at ignoring it.

Frankly, I think Roberts is giving Kennedy some of his own, after the raking he took for providing the 5th vote to uphold the mandate in ACA. Remember that while Roberts cast the deciding vote, his opinion (PDF), outside of his taxing power decision and (apparently the Medicaid expansion issue), did not carry a formal majority. The Chief Justice was in no box.

And neither is Kennedy. If he does not want to decide Windsor on equal protection grounds, he won't. He knows he carries the 5th vote either way. Just like the Chief Justice did in the ACA case.

Post script: This analysis also assumes that the Court will not reach the merits in the Prop. 8 case. I agree with that analysis, as I think the Court will decide that the petitioners lack standing.