Because judicial decisions have propelled American history, and because a long-standing judicial mistake needs to be rectified, the most compelling of the many reasons for electing Mitt Romney is that presidential elections shape two of the federal government’s three branches. Conservatives, however, cannot coherently make the case for Romney as a shaper of the judicial branch until they wean themselves, and perhaps him, from excessive respect for judicial “restraint” and condemnation of “activism.”

In eight years, Ronald Reagan appointed 49 percent of the federal judiciary; Bill Clinton appointed 43 percent. Clint Bolick says the power to nominate federal judges has become “the grand prize in presidential elections,” because presidents now choose appointees with special attention to judicial philosophy, and because human longevity has increased.

In his lapidary new book Two-Fer: Electing a President and a Supreme Court, Bolick, of the Hoover Institution at Stanford and the Goldwater Institute in Phoenix, notes that Reagan was systematic and successful in appointing judges who would not surprise him, and his successors have emulated him. Since Presisdent Obama appointed Elena Kagan to replace John Paul Stevens, whose liberalism surely surprised his appointer, Gerald Ford, the court’s liberals are Democratic appointees, the conservatives Republican appointees.

The average tenure of justices has grown from eight years in the young Republic to 24.5 years today. There have been four presidencies since Reagan’s, but two of his Supreme Court appointees, Antonin Scalia and Anthony Kennedy, still serve. Of the dozen justices confirmed since 1972, only one, Ruth Bader Ginsburg, was 60 when appointed. If Clarence Thomas, who was 43 when nominated, continues to the same age as the justice he replaced (Thurgood Marshall, 83) he will serve 40 years, eclipsing the court record of 36 (William Douglas).

Since Thomas replaced Marshall 21 years ago, no appointee has altered the court’s balance: Four liberals replaced liberals and two conservatives replaced conservatives. Today, however, two conservatives (Scalia and Kennedy) and two liberals (Ginsburg and Stephen Breyer) are in their 70s. So if Obama wins he may be able to create a liberal majority; if Romney wins he may be able to secure a conservative majority for a generation.

And, Bolick hopes, a conservative majority might rectify the court’s still-reverberating mistake in the 1873 slaughterhouse cases. It then took a cramped view of the 14th Amendment’s protection of Americans’ “privileges or immunities,” saying these did not include private property rights, freedom of contract and freedom from arbitrary government interference with the right to engage in enterprise. This led in the 1930s to the court formally declaring economic rights to be inferior to “fundamental” rights. This begot tolerance of capricious government abridgements of economic liberty.

On today’s court the leading advocate of judicial “restraint” is the liberal Breyer, who calls it “judicial modesty.” Contemporary liberalism regards government power equably, so the waxing of the state seems generally benign. Yet Romney promises to appoint “restrained” judges. If, however, the protection of liberty is the court’s principal purpose, it must not understand restraint as a dominant inclination to (in the language of Romney’s website) “leave the governance of the nation to elected representatives.”

Such as those elected representatives who imposed Obamacare’s individual mandate? Or those representatives who limited (with the McCain-Feingold law) the freedom of political speech of persons acting as individuals? Or those who limited (with the law Citizens United overturned) the speech rights of people associated in corporations? Or those who seized private property under eminent domain not for a clear “public use” but for any “public benefit” that enriches government? (This abuse was ratified by a “restrained” court majority in Kelo v. New London.)

“When courts fail to enforce the Constitution,” Bolick writes, “typically they say that the proper recourse is through democratic processes — which offers hollow comfort given that presumably it was democratic processes that created the constitutional violation in the first place.” As Madison warned: “Wherever the real power in a government lies, there is the danger of oppression,” and in this nation “the real power lies in the majority of the community.”

Although Hamilton called the judiciary the “least dangerous” branch because it has “neither force nor will, but merely judgment,” it is dangerous to liberty when it is unreasonably restrained. One hopes Romney recognizes that judicial deference to elected representatives can be dereliction of judicial duty.