In ordinary life, silence can be golden. Sensible and courteous people sometimes hold their tongues, especially on highly divisive questions. As last week's Supreme Court arguments over same-sex marriage attest, silence also plays a role in constitutional law.
Consider a little episode from Supreme Court history. In Poe v. Ullman, decided in 1961, the court was asked to strike down a Connecticut law forbidding the use of contraceptives. It declined to do so. But it also refused to rule that the law was constitutional.
Instead it said that the case wasn't "justiciable," in the technical sense that it wasn't appropriate for judicial review. The court's reason was that the law had hardly been enforced. The people who were challenging it (two married women and a male physician) didn't face the kind of immediate threat that would justify judicial intervention.
The court's technical argument wasn't unreasonable. But everyone knew that the court had the power to decide the case and that it chose not to do so.
The problem was that in 1961, the nation was in the midst of a large number of difficult debates about people's rights. Those debates involved not only contraception but also racial segregation, criminal justice, voting rights, freedom of speech, separation of church and state, and much more.
The court was a central part of those debates, and it didn't want to stir up further controversy. Its refusal to pronounce on the Connecticut law reflected a distinctive form of pragmatism. (It wasn't until 1965 that the court saw fit to strike down the law -- and to embark on a path of privacy protection that led directly to Roe v. Wade in 1973.)
The court's choice of silence in Poe v. Ullman doesn't stand on its own; it is part of a family. In 1956, the court adopted a similar approach in refusing to decide whether states could ban racial intermarriage. In 1974, the court declined to pronounce on the constitutionality of affirmative action in university admissions.
In recent years, the court has refused to resolve some important legal questions raised by the war on terrorism. If the arguments last week provide any clue, there is a good chance that the justices will also decline to settle the California dispute over same-sex marriage.
Why does the court opt for silence? There are two reasons, involving humility, on the one hand, and prudence on the other. First, the justices might be genuinely uncertain about what the Constitution requires, and they might want to learn more before offering their conclusion. Suppose that the constitutional validity of some practice depends on a disputed question of fact. What, for example, are the actual effects of affirmative- action policies in university admissions? A period of experience might help the court to obtain an answer.
Second, the court might believe that judicial intervention will damage both democratic processes and the judiciary itself. As early as 1961, the court might have been convinced that the Constitution prohibits states from forbidding the use of contraceptives. But the court might also have believed that with respect to sex and contraception, Americans were re-evaluating longstanding social norms -- and that nine people in black robes shouldn't disrupt that re-evaluation. And maybe the justices believed that by declining to intervene, they could protect their own political capital during a period in which the court was facing political attacks.
But if silence can be golden, it can also be irresponsible, even an abdication. Silence might authorize the perpetuation of real injustice -- and clear violations of the Constitution.
Suppose the court had been able to anticipate the terrible storm of protest that followed its 1954 decision in Brown v. Board of Education, forbidding racial segregation in education. Should the justices have struggled to find a way not to decide the case?
If the court opts for silence whenever it fears an intensely negative public reaction, it will vindicate the Constitution only in the easiest cases, when the public already agrees with it. If so, what would happen to the Constitution's role as a safeguard against the will of political majorities?
The argument for silence is greatly weakened when the Constitution speaks with clarity. If the court has no doubt about what the Constitution requires, and if the legal question is properly presented, silence is rarely a good idea. Yet if the democratic process is intensely focused on a particular topic, and if social understandings are in a genuine state of flux, there is a legitimate argument for caution.
In constitutional law, as in ordinary life, the line between cowardice and prudence can be thin, but it is prudent, and sometimes even brave, to try to draw it.
Cass R. Sunstein, the Robert Walmsley University Professor at Harvard Law School, is a Bloomberg View columnist. He is the former administrator of the White House Office of Information and Regulatory Affairs, the co-author of "Nudge" and author of "Simpler: The Future of Government," to be published on April 9.