The option of formal constitutional amendment cannot eliminate need for some judicial interpretation and often would contravene conservative principles. At the same time, process and principle constrain the core of judicial discretion our legal system requires.
The Practical and Inherent Limits of Amendment as Sole Means of Change
Contrary to the claim that meaning is frozen in time and new understanding emerges only from revising the 1788 text, amendment cannot practically accommodate all constitutional development. Many founders thought needs for change could be met by amendment more easily than our history has since proved. The 1788 Constitution has turned out to be one of the world's most change-resistant texts--with only seventeen amendments since the Bill of Rights--for two main reasons. First, our typical process, Congress passing proposals for states to ratify, poses a high practical hurdle. Today, for instance, Senators from a group of states collectively comprising only 7.5 percent of the population can deny the two-thirds Senate vote required for an amendment--a veto threshold twice as undemocratic as at our founding, reflecting increased population disparity between states. (The other, never-used option--a constitutional convention--is even less practical.) Second, we recognize that changing constitutional text introduces consequences hard to anticipate and reverse, a risk seldom warranted given our effective tradition of interpretation.
Minority rights do not depend on majority protection.
Most clearly, amendment cannot be sole guardian of unwritten inalienable rights. A national supermajority will not always rise and adopt amendments to constrain an abuse by majorities in particular states. And amendment can never remedy the present abuse of a right by act of Congress, that act expressing a national majority will that precludes existence of a supermajority wishing to protect the right. True, for some originally-unenumerated rights, the necessary national supermajorities eventually did arise and enshrine textual protection. We did abolish slavery. We did extend the right to vote, first to men of all races and eventually to women. But slavery's abomination persisted nearly a century after we claimed our independence to be justified by inalienable rights, finally eradicated only by an amendment born of civil war. And we cannot countenance generations of women being denied a political voice prior to 1920's ratification of the Nineteenth Amendment.
Denying judicial recognition of a right merely because amendment provides theoretical remedy, which supermajorities might someday implement, evokes the misguided thinking of Scott v. Sandford (the Dred Scott case). Dred Scott held that African Americans freed under applicable state law were, according the Court's flawed reading of founders' intent, too biologically and socially deficient to be considered "citizens" under the 1788 Constitution, a view that could not be disturbed absent amendment under that Court's narrow originalist philosophy.
If gay rights are fundamental, they require judicial protection.
Today, even ascendant national support for gay rights still falls short--far below thresholds for the congressional and state-by-state supermajorities required for proposing and then adopting a change to constitutional text. Such an amendment could be blocked in Congress by negative votes of senators from just seventeen states or denied ratification by just thirteen states. Because the 1788 Constitution's mechanism for formal change affords equal say to even the least-populated states, it matters that national support of same-sex marriage reflects strong-majority support in a relatively-small number of states, albeit many of the most-populated. Most federal senators from the opposing majority of states would follow their state's sentiment and vote against proposing any gay rights amendment. Or, should such a proposal garner two-thirds votes in the Senate and House, at least one-quarter of state legislatures or conventions would vote in opposition and thus deny ratification--at least in the near future.
The Court will treat the trend of state majorities favoring gay rights as supporting yet not deciding whether those rights presently are fundamental. Support for same-sex marriage peaks with younger voters and generally diminishes with each older age group. That suggests someday either (i) every state will recognize the right or (ii) a sufficient national supermajority will coalesce, agree on new constitutional wording, and adopt a gay-rights amendment. While rights would thus come for all gays through the political process--someday--as they ultimately did for the enslaved and women, our constitution does not countenance deferring an inalienable right. On the other hand, the Court sometimes considers societal trends as one factor for assessing whether a claimed unenumerated right is inalienable in the first place. For example, the Court recognized the widening judgment of states and foreign countries that executing one mentally incapable of understanding that punishment violates a fundamental right, and that was relevant in the Court's assessment of that claimed right under our constitution. Conversely, the Court might find the relatively-small number of our states that have thus far found denial of same-sex marriage to violate their state constitution, or have voted or legislated for gay rights, to be a factor against recognizing such a right to be inalienable today.
Acknowledging that majorities do not determine individual rights only moves the inquiry forward, into the grey reality of constitutional adjudication. For example, principles outside text establish that Dred Scott was wrongly decided. The Court in 1858 should have followed principles of basic human dignity, including those of our Declaration of Independence, and recognized that Scott was entitled to have his claim heard and could not be considered property. On gay marriage, the Court may soon decide whether similar principles of basic human dignity, precedent, and societal trends if deemed relevant, either establish the claimed unenumerated right or justify subjecting gay rights restrictions to heightened scrutiny under the Equal Protection Clause (as explained below).
Though those principles are grey, that analysis inherently fuzzy, the Court can articulate fundamental rights in a way that conforms to conservative values and reflects judicial restraint, as described below.
Judicial Interpretation's Conservative Character
I cannot conceive how any man can have brought himself to that pitch of presumption, to consider his country as nothing but carte blanche, upon which he may scribble whatever he pleases.
Edmund Burke (philosophical forebear of modern conservatism)