The reckless partisanship that has infected too much of American democracy is working its poison into the federal government’s judicial branch, to ill effect. Regrettably, the latest case in point involves Minnesotans. U.S. Sen. Al Franken’s decision to stand in the way of the nomination of Minnesota Supreme Court Associate Justice David Stras to the Eighth U.S. Circuit Court of Appeals is a disappointing new step down a worrisome road.

If the Senate’s traditional prerogative for a nominee’s home-state senators holds, Franken’s announcement Tuesday that he will not “return a blue slip” to the Senate Judiciary Committee ends Stras’ nomination. President Donald Trump would be obliged to send the Senate a new nominee. U.S. Sen. Amy Klobuchar acknowledged as much as she made the by-then moot point that she would have preferred to grant Stras the benefit of a hearing.

But there’s no guarantee that the blue-slip tradition will survive Franken’s move — not in light of the several breaches of Senate norms that blocked President Barack Obama’s appointment of Judge Merrick Garland to the U.S. Supreme Court last year and led this year to the installation of Justice Neil Gorsuch on the high court instead. After going so far as to junk the Senate’s filibuster rules to confirm Gorsuch, the GOP Senate majority might deem blowing up the blue-slip tradition a trivial matter. At least one conservative group promptly urged the Senate to take up the Stras nomination without Franken’s blessing.

The sharp-elbows partisanship that drove Republican decisions in the Garland and Gorsuch matters helps explain Franken’s decision. But it doesn’t justify it.

Franken’s stated objection to Stras was not that he is ill-qualified or deficient in character or ability — the sort of things that used to be the only reasons for home-state senators to block a judicial nomination. Neither did the Minnesota Democrat cite the one qualm we voiced when Stras was nominated in May: The Eighth Circuit bench has been populated with only two women and two people of color in its entire history, and it would benefit from more diversity.

Rather, Franken said he rejected Stras for one reason: the justice’s conservative views. Stras, Franken said, is too much in line with Supreme Court Justice Clarence Thomas, for whom Stras once clerked, and the late Justice Antonin Scalia. Franken predicted that “if confirmed, he would embrace the legacy of his role models and reliably rule in favor of powerful corporate interests over working people, and that he would place a high bar before plaintiffs seeking justice at work, at school, and at the ballot box.”

In response, we’d echo one of Stras’ former Minnesota Supreme Court colleagues, retired Justice Paul Anderson, who wrote on these pages: “While Stras is more conservative than I would like, that is not the point. The question is whether Stras is qualified to serve on the Eighth Circuit. And he is.”

Franken may succeed in stopping the Stras nomination. But as long as Trump is president and the Senate is in Republican control, Franken can’t keep a conservative jurist off the Eighth Circuit court. Instead, Franken is inviting the end of Minnesota’s informal claim on the seat long held by Judge Diana Murphy of Minneapolis, who now serves with senior status. Trump can be expected to nominate someone from another of the seven states in the circuit’s jurisdiction — likely one with no Democratic senators waiting to foil the nomination.

Further, Franken is not ending Stras’ judicial career. Stras continues to serve on the Minnesota Supreme Court, as he has since his appointment by GOP Gov. Tim Pawlenty in 2010, and can stand next year for re-election to another six-year term.

But by refusing to allow Stras to advance, Franken is succeeding in another, more ignoble way. He is mimicking and hence normalizing the Republicans’ treatment of Garland and Gorsuch. In so doing, Franken is deepening the infusion of the judicial branch with a corrosive partisan taint, and that is putting public trust in the courts at risk.