The U.S. Congress is in the midst of a breakdown in longstanding institutional norms. The latest example is the Senate’s refusal to hold confirmation hearings for Merrick Garland, President Barack Obama’s nominee for the Supreme Court -- a refusal that is probably without precedent. But something broader is occurring, and it threatens to undermine the federal government’s ability to carry out its central functions. To see what has happened and what might be done about it, we should say something about norms in general.

The place to start is the late Edna Ullmann-Margalit’s pathbreaking 1975 book, “The Emergence of Norms.” Ullmann-Margalit’s central claim, rooted in game theory, is that social norms are “solutions to problems posed by certain types of social interaction situations.” In her view, norms impose “a significant social pressure for conformity and against deviation,” and they usually prevail over selfish or purely personal considerations.

Ullmann-Margalit argued that norms help solve prisoner’s dilemmas, which arise when each person, relying on rational self-interest, acts in a way that makes everyone worse off. In those situations, mutually beneficial outcomes are possible only with a strong norm, backed by social pressures on those who violate it.

Suppose, for example, that the question is whether to pay your income tax, or clean up your garbage, or cut through your neighbor’s well-tended lawn. In each case, a social norm might turn out to be indispensable. In short, many norms turn out to be arms-control agreements, enforced by social pressures. We benefit from being able to take those norms for granted.

When institutions work well, it is usually because they too are guided by such norms. In the U.S. Congress, Democrats and Republicans have long adhered to norms involving the confirmation process, the filibuster, the subpoena power, committees, hearings and more. But in recent years, many of those norms have collapsed.

Take Supreme Court nominations. Before the Democrats’ refusal to confirm Judge Robert Bork in 1987, many people would have said that the Senate followed this straightforward norm: As long as Supreme Court nominees meet basic standards of competence and character, they will be confirmed. Democrats could say to Republicans, “so long as your nominees are neither stupid nor sleazy, they’ll get the job,” and Republicans could say exactly the same.

Whether or not the Senate always respected that norm, there’s no question that Bork’s defeat obliterated it. The new norm looked like this: If the opposing party believes that the views of Supreme Court nominees are out of the mainstream, then it can legitimately oppose them.

That norm was also a sort of arms-control agreement. For example, Anthony Kennedy and David Souter were moderates, unquestionably within the mainstream, and they were confirmed by overwhelming votes (97 to 0 for Kennedy, 90 to 9 for Souter).

The post-Bork norm eventually broke down too. You can argue about exactly when that happened. It may have been the divided vote over John Roberts (who had 22 votes against him). It may have been the even greater split over Samuel Alito (42 negative votes).

After the Alito vote, the new norm could be described this way: If senators (or their constituents) strongly disagree with a nominee’s predicted votes, they can legitimately vote against confirmation. That’s consistent with the large number of votes against confirming Sonia Sotomayor (31) and Elena Kagan (37).

With the Republicans’ refusal to allow a vote on Garland, we’ve entered uncharted territory. The GOP would like to say that the norm for which they are speaking is quite narrow: No Supreme Court confirmations in an election year.

But their behavior is fully consistent with a much broader one: If a party can get away with refusing to confirm a Supreme Court nominee chosen by a president of the opposing party, that’s exactly what it will do. If so, appointments to the high court will become mired in the crassest form of partisan politics.

As Ullmann-Margalit’s work suggests, it is exceedingly difficult to reinstate an abandoned norm, for one reason: Individuals lack an incentive to adhere to it. That’s certainly true in the Senate, especially in the period before an election. The breakdown of longstanding norms may turn out to be permanent.

To know whether that’s a problem, we need to examine the consequences. If a president has difficulty filling positions because the opposing party delays confirmation, the people’s business might not get done. And if a president’s judicial nominees are not confirmed, because the opposing party disagrees with their likely votes, federal courts will lack sufficient personnel to proceed expeditiously. Blocking important legislation, as a way of punishing the president of the opposing party, is even worse; consider the absence of funding for needed infrastructure improvements.

There is some hope. It lies in the critical period between November 2016 and February 2017, when a new president and lawmakers will be in a position to establish new patterns of behavior. In the immediate aftermath of a presidential election, legislators are far less constrained by short-term political calculations, and they have the freedom to pursue the nation’s long-term interests. The proper functioning of our institutions may well depend on that.

By Cass R. Sunstein

Cass R. Sunstein, the former administrator of the White House Office of Information and Regulatory Affairs, is the Robert Walmsley university professor at Harvard Law School and a Bloomberg View columnist. -- Ed.