A president’s power to nominate federal judges, above all U.S. Supreme Court justices, fuels an ever-intensifying storm of controversy in national politics — witness the overheated debate already surrounding the nomination of Judge Brett Kavanaugh, President Donald Trump’s second pick for the high court, whose confirmation hearing is expected next month.

Minnesota voters pondering their choices in Tuesday’s primary may want to give some thought to a governor’s sweeping power to reshape state courts, including the Minnesota Supreme Court.

As it happens, a potentially far-reaching state Supreme Court ruling handed down in July suggests how swiftly and significantly a governor can change a court — and how much can be at stake.

Unlike federal judges, who enjoy life tenure and often serve to advanced ages, state judges must by law retire by age 70. Some call it quits earlier, or move on to the federal bench. The result is that governors tend to get relatively more chances to pick judges than presidents do (and that their imprint on courts is shorter-lived).

In their eight-year tenures, Presidents Barack Obama and George W. Bush each put two justices on the nine-member U.S. Supreme Court. Trump has now made two nominations.

In his eight-year tenure, DFL Gov. Mark Dayton put six justices on the Minnesota Supreme Court. Five of his picks remain on that seven-member court. In two terms preceding Dayton’s, Republican Tim Pawlenty appointed five justices.

What’s more, a governor’s judicial appointees face no Senate confirmation gauntlet as federal nominees do. A governor’s choices are promptly seated. State judges do have to stand for re-election every six years. But Minnesota has managed to keep judicial elections low-key, low-cost, mainly depoliticized affairs.

Most thoughtful observers agree that an independent judiciary, insulated in this way from high-intensity partisan politics, is a critical asset to democratic government, and one not all states enjoy.

The main reason things might ever change on this score in Minnesota would be if the court were tempted to politicize itself — to overreach and claim power to make the kinds of decisions voters are inevitably going to want a say in.

That’s the treacherous road the justices may have wandered onto with their July 25 decision in Cruz-Guzman vs. Minnesota, an Education Clause case that divided the court along the kind of partisan, ideological lines that have become familiar at the U.S. high court but are still somewhat unusual in St. Paul.

Four Dayton appointees joined in a majority opinion from which the court’s two remaining Pawlenty appointees dissented. (The fifth current justice appointed by Dayton had not joined the court in time to participate in this case.)

The seemingly modest ruling merely allows a lawsuit to proceed — a suit alleging that Minnesota is failing to provide an adequate education to disadvantaged urban students.

But the issue at bottom, as the impressive dissent of Justice G. Barry Anderson puts it, is about “the enduring obligation of the judiciary to maintain its rightful role … in our constitutional form of government.”

The three-year-old litigation argues that Minnesota’s education policies — charter schools, open enrollment, district and attendance boundaries, etc. — have segregated poor and minority pupils in city schools and that this has prevented their receiving an “adequate” education, in violation of the state Constitution.

It is not an ordinary discrimination case but focuses on the broader question “whether,” as Justice Natalie Hudson explained for the court, “the Legislature has violated its constitutional duty to provide ‘a general and uniform system of public schools’ that is ‘thorough and efficient,’ ” as the Minnesota Constitution commands.

A unanimous appeals court panel had dismissed the case (two Pawlenty appointees and one Dayton appointee, for what it’s worth). Those judges ruled that the question of what constitutes an “adequate” education and how best to provide it — at least apart from objective matters such as equitable funding levels — is a “nonjusticeable political question.”

That is, they held that it simply is not what Anderson calls the “rightful role” of courts to answer such a question. Legal reasoning can’t reveal how best to organize and run schools. It involves the kind of subjective policy judgments that legislators and governors and school boards are supposed to make through the political process, with its freewheeling debates and negotiated compromises and frequent shifts of power and other mechanisms through which the will of the people is expressed.

Hudson and the Supreme Court majority emphasized that the lawsuit doesn’t ask courts to “devise particular educational policies to remedy constitutional violations.” It only asks the judiciary to order the Legislature and governor to do better.

But Anderson sensibly notes that this will simply invite more litigation over the “adequacy” of any remedies the Legislature and governor obediently devise. Henceforth, “the Judicial Branch,” Anderson wrote, “will have final approval over” policy choices that are “inherently subjective, undefined … deeply political [and] for which the judiciary has no demonstrable expertise.”

Fact is, another lawsuit relying on the “adequate education” doctrine is already pending before the Minnesota Supreme Court. This one, Forslund vs. Minnesota, emerges from conservative school reform circles and claims that teacher tenure policies make it difficult to jettison lousy teachers — so they must be unconstitutional.

Well, why not?

Anderson warns of unspecified “consequences” for the judiciary from this kind of political “entanglement.” Maybe he means that other groups of parents and advocates, not to mention teachers unions and education reform lobbies, are just apt to notice if Minnesota’s courts in effect take over the state’s schools. And at that point their patience with low-budget, low-volume judicial elections may wane.

In the meantime, this ruling is a reminder that the healthier way for politics to intersect with courts is for voters to think carefully about the kinds of judges various candidates for governor might select.

D.J. Tice is at Doug.Tice@startribune.com.