There are exceptions to the rule that you can’t be a judge if your résumé provides a window into your politics. Jane Kelly, one of a few judges whom President Obama was said to have interviewed before deciding on Judge Garland, was a public defender before becoming a judge.

Nevertheless, the path to the Supreme Court grows narrower with each passing year. Justice Ruth Bader Ginsburg was a pioneering women’s rights lawyer for the A.C.L.U. before her nomination to the federal bench. But she lamented in 2011 that her “A.C.L.U. connection would probably disqualify me” if she were put forward for the Supreme Court today.

That’s not to say that excellent judges cannot rise to our nation’s highest court. Judge Garland’s record as a court of appeals judge suggests that he is one of them. Nor should Judge Garland be punished for amassing credentials that set him up for the Supreme Court. Don’t hate the player. Hate the game.

Although the apparent consensus that Supreme Court justices must have gone to Harvard or Yale is a relatively recent development, there’s always been a strong thread of elitism running through the legal profession’s highest reaches. Alexis de Tocqueville wrote very early in our nation’s history that “American aristocracy is found at the bar and on the bench.”

In their decisions, these American aristocrats blessed segregation, struck down child labor laws, upheld Japanese internment camps, permitted states to sterilize women against their will, gutted the Voting Rights Act and ushered a torrent of money into our politics.

This grim history should be a warning to lawyers eager to win policy fights in the courts that should be left to the democratic process. Some of the court’s worst decisions were the product of rigid ideology. But many are rooted in the fact that the justices in the majority lacked what President Obama said he was looking for in a nominee: “an understanding of the way the world really works.” Without that understanding, a judge cannot grasp what life is like for people who have not successfully climbed to the top of a legal aristocracy, often at the expense of other pursuits. It is difficult to imagine, for example, that the Roberts Court would have cast such a skeptical eye on campaign finance laws if many of its members had run for office and witnessed firsthand how money corrupted politics.

Should liberals gain a majority on the Supreme Court, their biggest challenge will be policing the line between their legitimate constitutional grievances and disputes that should be left to the elected branches. Conservatives gave in too often to temptation while they held a majority on the court — just consider the series of challenges to Obamacare that made their way to the court. If the balance of power shifts, liberals would make a terrible mistake by following their example.

America is rooted in the idea that legitimate authority to govern flows only from the consent of the governed. Meritocracy and respect for credentials both have their place in a society that needs competent leaders to hold the reins of government. But elite credentials cannot teach a judge what it means to seek shelter in the law, or how it feels to be a victim of discrimination. And a wise judge must understand his own limitations.