Just because today’s opinion was expected by all doesn’t make it any less momentous. A five-justice majority writing through Justice Kennedy finds that there’s a constitutional right for gay and lesbian couples to get marriage licenses — at least so long as everyone else gets them. (We’ll set aside the question of why the government is involved in marriage in the first place for a later time.)

In sometimes-soaring rhetoric Kennedy explains why the Fourteenth Amendment’s guarantee of both substantive liberty and equality means there is no further valid reason to deny this particular institution, the benefit of these particular laws, to gay and lesbian couples.

Not surprisingly, all four conservative justices dissented. Indeed, it’s interesting that each of them wrote his own dissent, each riffing on the same theme. That is, regardless of your views of how to define marriage this is a decision that should be left to the people in their states, not to courts.

Chief Justice John Roberts in particular said that people who benefit from today’s ruling should celebrate it, should celebrate this development in our society. But make no bones about it, this doesn’t relate to the Constitution. (Where was this principled logic yesterday?)

In any event, this will be a case that is studied for generations. There aren’t clear, bright-line rules about levels of scrutiny or any other legalisms — avoiding that artifice is all to the good — and it’s a landmark ruling that shows how far we’ve come. It was in 2003 that the Court had to invalidate the criminalization of gay sex and a mere 12 years later it commands state officials to issue marriage licenses to same-sex couples.

Good for the Court — and I echo Justice Kennedy’s hope that both sides now respect each other’s liberties and the rule of law.