ST. PAUL (AP) — Minnesota Supreme Court Associate Justice Christopher Dietzen announced Thursday that he’s resigning at the end of August, giving Democratic Gov. Mark Dayton the opportunity to appoint a majority of justices on the seven-member court.

The 69-year-old associate justice said in an interview his decision to depart was a practical matter: He’ll hit the state’s mandatory retirement age of 70 in March. While he could have let voters pick his successor in the November election, he said he thought it better to leave it up to the governor and the state’s Commission on Judicial Selection, which helps find and recommend candidates.

Dietzen, who was appointed by Republican Gov. Tim Pawlenty in 2007, recognized the possible political backlash of leaving the decision up to a Democratic governor who can now name a fourth appointee to the state’s highest court. His successor will face voters in 2018.

“To the people who may question my sanity — and many have, others will continue to — I have to make a decision that I think is the right decision,” he said. “That’s what I did.”

Dietzen officially joined the high court in 2008 after four years on the Minnesota Court of Appeals and a career in private practice. His resignation is effective Aug. 31.

Dayton thanked Dietzen for his service on the court, noting he and the commission will work to find a suitable replacement.

“For eight years, Justice Christopher Dietzen has served the people of Minnesota on our state’s Supreme Court with honor and distinction,” the governor said in a statement.

Three current associate justices on the Supreme Court are Dayton appointees — Margaret Chutich, Natalie Hudson and David Lillehaug. Dayton’s only other appointee to the high court was Wilhelmina Wright, who later became a federal judge.

Dietzen said he understood his time was limited when he took the job in 2008 (“It was a matter of mathematics,” he said). Still, he wasn’t quite ready to leave the court.

“If I could, I would serve,” he said. “I love the work. I have a passion for the work.”

That work recently took him into controversial territory. He led a controversial effort to drastically reduce sentences for many drug offenders as chair of Minnesota’s Sentencing Guidelines Commission. Those changes, slashing sentences for first-degree drug possession and reducing second-degree charges to a likely probation sentence, will take effect in August unless if the Legislature intervenes.

Dietzen stood by those reductions but declined to offer advice or guidance to the Legislature, where some members have suggested they’ll block them.

Chief Justice Lorie Skjerven Gildea, another Pawlenty appointee, said Dietzen will be greatly missed.

“For more than a decade, Justice Dietzen served our court system admirably, both as a wise and thoughtful jurist, as well as a leader in our efforts to improve the administration of justice in our state,” she said.