A common criticism of Supreme Court nominee (now Justice) Brett Kavanaugh was that he is “outside the judicial mainstream.”

While that epithet has a long history in judicial confirmation fights, no one really knows what it means. And if Kavanaugh’s approach to judging is outside the mainstream, America is really in trouble.

As an accusation against judicial nominees, this seems to have originated with President Ronald Reagan’s 1987 nomination of Robert Bork to the Supreme Court.

Bork represented the view that the meaning of the Constitution and statutes does not change from the time they were originally enacted. Deciding cases requires a judge to determine that original meaning and apply it to the facts before him. Judges may not change the meaning of the law in order to make cases come out the way they want.

This is how America’s founders designed the judiciary to function. In 1795, the Supreme Court put it this way: “The Constitution is fixed and certain; it contains the permanent will of the people, and is the supreme law of the land.”

Thomas Jefferson described the role for the judiciary that the founders rejected. If judges controlled what the Constitution means, he wrote, it would be “a mere thing of wax in the hands of the judiciary, which they may twist and shape into any form they please.”

By the 1930s, however, Congress wanted much more power over the economy than the Constitution actually provided. President Franklin Roosevelt began replacing Supreme Court justices who saw the Constitution as “fixed and certain” with those who saw it as a “mere thing of wax.” As a result, the federal government grew much more powerful at the expense of the states, and the American people’s ability to decide how their country is run steadily diminished.

Reagan, who was elected in 1980, promised to reverse that trend. In 1985, Attorney General Edwin Meese explained to the American Bar Association that judges viewing the Constitution’s meaning as fixed and certain was simply “the logical result of the philosophic foundations of our legal system.”

While the traditional view of the judiciary’s role had certainly been challenged by 1987, it was bizarre to call it “outside the mainstream” altogether. After all, isn’t the logical result of our legal system’s foundations the literal definition of the mainstream?

Since 1987, the label “mainstream” has come to simply mean whatever someone finds preferable. In October 1994, for example, the New York Times said that President Bill Clinton’s judicial appointments were “well in the mainstream,” but, almost to the day in 2003, said that President George W. Bush’s judicial picks were “out of the mainstream.”

With that background, let’s look again at the charge that Kavanaugh is out of the mainstream.

Half of the judges in active service during his 12 years on the U.S. Court of Appeals for the D.C. Circuit were appointed by Democratic presidents. Yet Kavanaugh was in the majority in 97 of the cases in which he wrote an opinion.

When Kavanaugh served on the same three-judge panel as now-Chief Judge Merrick Garland (a Clinton appointee), Kavanaugh joined 93 percent of Garland’s opinions and Garland joined 96 percent of his. Out of the mainstream?

But since Bork’s nomination, the opposition has evolved in another concerning way.

While Bork’s opponents said that the method or approach he used to decide cases placed him outside the mainstream, Kavanaugh’s opponents took issue with the results of his method or approach, and on that basis said he is outside the mainstream. Decisions they like, or that favor their preferred political interests, are in the mainstream. Others are not.

Kavanaugh’s decisions limiting federal agencies’ power to issue environmental regulations, for example, were out of the mainstream. Strangely, however, his critics altogether ignored his decisions upholding environmental regulations (detailed here).

If the “mainstream” is to be found only by looking in the political mirror, however, Democrats and their allies on the left have come to the point where they will not accept any judicial nominee from a Republican president.

The better view is to return to the principles provided by America’s founders. The judicial mainstream is, as Meese put it, the logical result of the foundations of our legal system. That logical result is a defined role for the judiciary in which judges treat the Constitution as fixed and certain, rather than a thing of wax.