The Supreme Court last week heard oral argument in the case of Hollingsworth v. Perry, which could shape the future of marriage in America. Regardless of its effect on marriage, it certainly will shape the future of American constitutional law.

The court has to decide whether California’s Proposition 8, which overrode a state court decision establishing same-sex marriage, violates the Equal Protection Clause of the Fourteenth Amendment.

Broadly speaking, the court might rule in one of three ways. It might uphold Proposition 8 and the voters’ rights to decide on marriage. It might rule that the federal constitution mandates same-sex marriage throughout the country. Or it might hold Proposition 8 unconstitutional, but without immediately overturning the marriage laws of other states.

Each approach would resonate with a different aspect of our constitutional traditions.

If the court approves Proposition 8, it will reaffirm the principle that governments “derive their just powers from the consent of the governed,” as the Declaration of Independence asserts. This principle suggests that the Constitution derives its authority from the fact that it was actually voted on by politicians trying to represent the wishes of their constituents.

No one supposes that the people who ratified the Fourteenth Amendment back in 1868 would have understood that amendment to have called into question the constitutionality of traditional, gendered marriage, and no one can imagine that the amendment would have been ratified at that time if the voters had been told that it would have such an effect.

Since We the People never voted to enshrine the modern principle of marriage equality in the Constitution, the court could reasonably conclude that the definition of marriage should be left to the ordinary political processes in the states.

Another part of our constitutional tradition, however, tells us that all persons are endowed with “unalienable rights” that are not to be left to the whims of voters. This principle suggests that the Constitution derives its authority, not so much from the fact that some people now long dead and gone voted on it, but from the fact that it secures for us, in the present, the protection of basic rights that are required by a sound understanding of morality.

On this view, it doesn’t matter that no one in 1868 thought that the Equal Protection Clause might challenge the traditional conception of marriage. Nor does it especially matter that the Supreme Court, back in 1972, dismissed for “want of a substantial federal question” the first case to assert a constitutional right to same-sex marriage.

What matters, on this understanding, is the proper understanding of equal protection today. If restricting “marriage” to opposite-sex couples offends the correct understanding of what equality requires, then laws establishing gendered marriage cannot be allowed to stand, no matter how popular they may be.

The problem with this approach is that it is not obvious that, over the long sweep of history, the Supreme Court justices have any more access to the truth about morality than the rest of us. If we want to celebrate the court’s wisdom for dismantling racial segregation, for example, we must also remember that the court had previously approved it.

Hence the appeal of a third tradition of incremental decision-making, which has its roots in the jurisprudence of the common law. On this view, the courts need to recognize that the Constitution’s meaning evolves over time, as the second theory holds. But on this view, the justices should not imagine that the Constitution necessarily mandates whatever any five of them happen to believe is morally required just now. Instead, like the first view, this theory requires some measure of deference to the judgment of actual voters.

These incrementalist judges hold that they should interpret the Constitution’s broad guarantees in light of the principles that have come to be established in state laws and state constitutions.

When the Supreme Court declared a fundamental right to use contraceptives, for example, only two states still prohibited their use. That ruling is now almost universally embraced.

Roe v. Wade, by contrast, remains enduringly divisive — perhaps because it invalidated the abortion laws of forty-six states. That only nine states (including Maine) now authorize same-sex marriages would suggest to the incrementalist that the time is not ripe for a broad ruling about marriage.

When the court issues its decision, probably in late June, we may learn something about the justices’ views about marriage, but we’ll certainly get a much clearer insight into their understanding of our Constitution.

Joseph R. Reisert is associate professor of American constitutional law and chairman of the department of government at Colby College in Waterville.