Conventional wisdom formed quickly this week after oral arguments in the two same-sex marriage cases before the U.S. Supreme Court. The gist is that the court would duck the fundamental question of whether the Constitution guarantees everyone the right to marry -- implied in the California Proposition 8 case -- and strike down the Federal Defense of Marriage Act on the limited ground that it interferes with states’ rights.

Don’t be too sure. It’s not just that oral arguments can be deceiving. (Remember the broccoli obsession in the Obamacare arguments? Almost no one thought Chief Justice John Roberts would provide the deciding vote to uphold the law.)

Justice Anthony Kennedy, the perennial swing voter, might well prefer some gradual way to introduce gay marriage without producing the headline “Court Grants Gay Marriage.” But the problem with this gradual strategy envisioned by court observers and attributed to Kennedy is that it would create anomalies leading to a nightmarish barrage of new litigation. Instead of attenuating criticism of the court by avoiding a single “Eureka” moment, the court would put itself, along with lower courts, at the center of hundreds more headlines for years to come. And they would all be of the same ilk: “Court Creates Legal Nightmare; Citizens on All Sides Angry.”

Messy Benefits

To understand the mess that would result if the court struck down DOMA without finding a general right to same-sex marriage, consider what would happen if the federal government recognized marriages performed in states that allow gay couples to marry while continuing to deny marital status to couples in other states.

In the first, most optimistic scenario, one or several marriage-friendly states might allow anyone from any state to get married there, creating a Las Vegas-style business in same-sex marriage. Gay couples would return to their home states with a piece of paper that should, in principle, entitle them to federal marital tax status, immigration benefits and more. But their home states would probably decline to recognize those out-of-state marriages, and deny them state-level marriage benefits.

If the Supreme Court’s decision to strike down DOMA depended on finding that states have an inherent right to define marriage in which the federal government cannot infringe, then the home states’ policy would probably be upheld. The result would be couples who are both married and unmarried for purposes of the same tax returns, mortgages and hospital visits. Each of these conflicts would be brought to the courts. State and federal courts would probably render divergent conclusions -- across all 50 states and 13 federal circuits. If this isn’t legal chaos, nothing is.

If no state wanted to attract business by becoming the same-sex-marriage hub for out-of-state residents, then the anomaly would arise when legally married gay couples moved to states that didn’t recognize their unions. Presumably they would nevertheless bring their federal benefits with them -- giving rise to the same legal issues just described. The only difference would be that litigation would build up slowly, rather than overnight. And what, pray tell, would happen if some of those couples wanted to get divorced but found themselves in legal limbo because their original states of marriage refused to administer a divorce while they lived far away? Would the federal government treat them as divorced even without a state-issued document to that effect?

Two Marriages

Some scenarios are downright funny. Suppose I married someone of the same sex in New York and that marriage wasn’t recognized in Pennsylvania. If I then decided to marry someone of the opposite sex in Pennsylvania, the state would presumably recognize that marriage while New York recognized my previous one. And both marriages would be recognized by the federal government, which would treat me as a lawful bigamist. That would be good news for 19th century Mormons, who were denied a federal constitutional right to plural marriage -- but most people today would find the conclusion truly bizarre.

The federal government couldn’t easily get out of this bind by saying it only recognized one valid marriage at a time, because in this scenario the court would have announced that the definition of marriage was fundamentally up to states. Recognizing only the New York marriage would violate Pennsylvania’s right to ignore the New York decision.

Examples could be multiplied, but you get the point. Today, non-recognition doesn’t have any real federal redress or create the situation where you are federally married and not state-married at the same time. Tomorrow, the problems that already exist in a world where some states recognize same-sex marriage and others don’t would be compounded and thrown into the federal courts.

The court’s supposed motivation to avoid declaring a general right to same-sex marriage is to allow the political process to take its course, and not impose a unified federal solution before everybody’s ready to accept it. Those with this cautious view like to cite Roe v. Wade as an example of a federal constitutional right that was granted before its time, creating a major backlash. Some would even go so far as to say that Brown v. Board of Education came too soon, as evidenced by Southern resistance to desegregation -- this despite the court’s infamous declaration that its mandate should be implemented “with all deliberate speed.”

But this theory relies on the assumption that even a messy political process would be superior to judicial fiat because it would leave the courts out of the equation. A partial or split decision on same-sex marriage would have the opposite effect. Instead of promoting what the great Alexander Bickel called the “passive virtue” of judicial prudence, it would put judges front and center on the issue for the foreseeable future. From the court’s perspective, it would be easier just to do the right thing. Here’s hoping Anthony Kennedy sees it that way.

(Noah Feldman, a law professor at Harvard University and the author of the forthcoming “Cool War: The Future of Global Competition,” is a Bloomberg View columnist. Follow him on Twitter. The opinions expressed are his own.)

To contact the writer of this article: Noah Feldman at noah_feldman@harvard.edu.

To contact the editor responsible for this article: Francis Wilkinson at fwilkinson1@bloomberg.net.