WASHINGTON -- Almost 35 years have passed since the Supreme Court decided to end America's argument about abortion. Because of the court's supposedly therapeutic intervention in the nation's supposedly inadequate democratic debate about that subject, the issue still generates an irritable irrationality that was largely absent prior to 1973.

Then, America was operating under a regime of moral federalism. In the absence of ukases from the federal judiciary that generate continentwide eruptions of tension and anger, many states were re-examining their abortion regulations, and many were relaxing them. To sample today's confusions, consider California.

There the electorate so strongly supports abortion rights that no right-to-life candidate for governor, U.S. senator or president has won in California since 1988. This is so in spite of the fact that a governor, U.S. senator or president has only slight relevance to the status of Californians' abortion rights.

Nevertheless, it is said that if the Republican Party wants to be competitive in California in presidential politics, it must nominate a pro-choice candidate, of which there is only one -- Rudy Giuliani. This is almost certainly true. It certainly is irrational because pro-choice Californians have next to nothing to fear -- just as pro-life Californians have next to nothing to hope for -- from a right-to-life president. The practical consequences of such a president concerning abortion would not differ significantly from Giuliani's consequences. Here is why.

Abortion policy is almost entirely in the custody of the U.S. Supreme Court, and will remain so unless or until the court decides to restore moral federalism regarding the issue. On Jan. 20, 2009, when the next president is inaugurated, the court will have one justice in his late 60s (David Souter, 69), four justices in their 70s (Steven Breyer, 70; Anthony Kennedy and Antonin Scalia, 72; Ruth Bader Ginsburg, 75) and one 88-year-old, John Paul Stevens. The two who will be oldest, Ginsburg and Stevens, are strong supporters of a constitutional right to abortion. The three who will be youngest -- John Roberts, 53; Samuel Alito, 58; Clarence Thomas, 60 -- seem unsympathetic to the court's abortion jurisprudence.

The next president probably will have an opportunity to significantly shape the court, which has frequently divided 5-4 on important questions, including abortion issues. But regarding abortion, the reasonable response to this fact from residents of many, perhaps most, states, and especially from Californians, should be a shrug of a question -- "So what?"

Suppose Giuliani or some other Republican becomes president and responds to a court vacancy the way all the Republican candidates promise to, with a nominee similar to Scalia, Thomas, Roberts and Alito. And suppose a case gives the court an opportunity to overturn Roe v. Wade. And suppose it does so.

Pause here a moment. This third supposition is somewhat dubious, because one of the justices who thinks Roe was improperly decided might nevertheless reason as Chief Justice William Rehnquist finally did concerning the "Miranda rights" of arrested persons -- the right, arising from a 1966 ruling, to be notified of their right to counsel and their right to remain silent. Rehnquist repeatedly and strongly argued that the Constitution, properly read, did not require the ruling, which he thought impeded effective police work. But when in 2000 a case gave the court an opportunity to overrule Miranda, Rehnquist wrote the majority opinion in a 7-2 decision upholding it. He wrote:

"Miranda has become embedded in routine police practice to the point where the warnings have become part of our national culture. While we have overruled our precedents when subsequent cases have undermined their doctrinal underpinnings, we do not believe that this has happened to the Miranda decision."

So, the overturning of Roe might not result from a Republican president's alteration of the court's balance. But suppose it did.

Again, so what? Many, perhaps most, Americans, foggy about the workings of their government, think that overturning Roe would make abortion, one of the nation's most common surgical procedures, illegal everywhere. All it actually would do is restore abortion as a practice subject to state regulation. But because Californians are content with current abortion law, their legislature probably would adopt it in state law.

It is not irrational for voters to care deeply about a candidate's stance regarding abortion because that stance is accurately considered an important signifier of the candidate's sensibilities and sympathies, and of his or her notion of sound constitutional reasoning. But regarding abortion itself, what a candidate thinks about abortion rights is not especially important.