Go ahead...I dare ya!

SO IS THIS WHAT a constitutional revolution looks like, when it starts? Americans have grown used to the idea that abortion rights, as established by Roe v. Wade, are getting chipped away at-by parental-consent laws, waiting periods, and the like. But the law signed last month by South Dakota's governor banning virtually all abortions represents a startlingly direct attack on the landmark decision.

Soon after, on the group weblog LawCulture, Jessica Silbey, an assistant law professor at Suffolk University, wondered aloud whether the South Dakota legislators had violated their oaths to uphold the Constitution by passing such a blatantly unconstitutional law. ''Really," Silbey wrote, ''isn't there a constitutional problem when state legislatures openly defy the Supreme Court of the United States in an effort to egg on its newest members to reverse entrenched precedent?"

Silbey even had a clever coinage for her explanation of why South Dakota's frontal attack was dubious: the ''dare doctrine." The state, she noted, made no pretense of playing by the rules the court has laid down in Roe and the several cases upholding it: South Dakota simply dared the court to upend 33 years of precedent-or, looked at another way, dared the court to defend Roe, a decision that quite clearly makes several justices uncomfortable. (Since Roe still has the support of five of nine justices, even with the addition of Justices John Roberts and Samuel Alito, South Dakota's gambit probably depends on the retirement or death of Justice John Paul Stevens, a liberal who is 86.)

To be sure, the move carries at least the whiff of rebellion. If South Dakota legislators are bold enough to flout the Supreme Court's recent decisions, couldn't they possibly be bold enough to ignore the court if and when it strikes down the new law? Could we see an antiabortion president sending troops into a defiantly antiabortion state, along the lines of when President Eisenhower had to send troops into Little Rock to enforce Brown v. Board of Education?

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OK, we're getting a little ahead of ourselves. Still, Silbey suggests that if a new court took up the dare, it would shake public faith in the institution. ''You want to think that there are some principled rules being made," Silbey says in an interview. For a new court to suddenly say ''never mind" to a decision, and all those that led up to it, would suggest that ''who is on the court determines what the law is all about," she says

The court, for its part, doesn't seem to appreciate being dared. In a decision this term, the court expressed annoyance with the New Hampshire Legislature for passing a parental-consent law that didn't include an exception for instances when the health of the mother is in jeopardy-essentially daring the court to fix the problem or strike down the law.

Silbey's argument, in fact, sounds a lot like one Justices Sandra Day O'Connor, Anthony Kennedy, and David Souter made in 1992, in Planned Parenthood of Southeastern Pa. v. Casey, the landmark case reaffirming Roe. While abortion was still controversial, they said, and some justices had moral qualms about it, to appear to overturn the decision simply because the court's membership had changed since 1973, ''would subvert the court's legitimacy beyond any question."

Of course, South Dakota legislators would retort (and Justices Antonin Scalia and Clarence Thomas would agree with them) that it's Roe that subverts the court's legitimacy-and that the court has survived abrupt about-faces before. In Brown v. Board of Education, in 1954, the court famously tossed out the ''separate but equal" doctrine that it had upheld since 1896. And in West Coast Hotel v. Parish, in 1937, the court abandoned its decades-old view that minimum-wage and maximum-hours laws interfered with individual liberty.

But unlike the principles underpinning Roe, hadn't those constitutional doctrines proved clearly unworkable? Certainly conservatives in 1937 and segregationists in 1954-and legal theorists concerned about consistency on the court-didn't think so.

The issue of abortion aside, law professors say, South Dakota's move awakens a notion that has been dormant in recent decades: the idea that it's not just the Supreme Court that decides what the Constitution means. During the second half of the 20th century, liberals complacently came to see the court as the enforcer of rights they held dear. ''Until the 20th century I don't think anyone would have been provoked by the idea the Supreme Court wasn't the last word" when it comes to understanding the Constitution, says Michael J. Klarman, a visiting professor of law at Harvard and author of ''Jim Crow to Civil Rights: The Supreme Court and the Struggle for Racial Equality" (2004).

Abraham Lincoln had no qualms about declaring, in 1858, that if he were in Congress, he would vote to ban slavery in the Western territories-even though the Supreme Court had just ruled, in Dred Scott, that to do so would be unconstitutional. (Lincoln won that argument in the end. Not a heartening parallel, if your goal is peaceful resolution of the abortion question.) Less cataclysmically, in the 1930s, Congress kept passing ''unconstitutional" bills regulating the economy, until the Supreme Court caved (for reasons scholars still debate).

More recently, after the court's Miranda v. Arizona decision, in 1966, which declared that police had to read suspects their rights or any confession would be invalid, Congress passed a law essentially undoing the decision when it came to federal crimes. (It said judges should look at each confession case by case.) That law, however, was hardly used, and the Supreme Court didn't take up its constitutionality until 2000. It struck it down.

But in more serious games of constitutional chicken, someone has to blink or the system falls apart. It's become commonplace in legal studies today-thanks to the work of Klarman and others-to say that the court can't get too far out in front of, or lag too far behind, the electorate's view of what is and is not constitutional. Each side nudges and prods the other, and constitutional dares are ways of showing where ''the people" stand. Appropriately, by this logic, liberal South Dakotans are now asserting their own constitutional views through a campaign to undo the new law via referendum.

Martin Lederman, a visiting professor at Georgetown Law Center who debated the ''dare doctrine" with Silbey on LawCulture, says there's only one situation when passing ''unconstitutional" laws is clearly inappropriate: when you have zero chance of persuading the court you're right. ''Then it strikes me as political gamesmanship and grandstanding that violates what I'd call constitutional etiquette," he says.

South Dakota faces long odds. But one suspects that what is most unsettling to some people is not the challenge itself, but that it has at least a prayer of succeeding.

Christopher Shea's column appears biweekly in Ideas. E-mail critical.faculties@verizon.net.