DFL Gov. Mark Dayton elevated former House Speaker Paul Thissen to the Minnesota Supreme Court on Tuesday, giving the highest court in the state a five-member progressive majority that’s likely to endure long after the governor leaves office.

Dayton appointed Thissen to fill an open seat on the court, selecting an attorney who has been a DFL state representative since 2003. Thissen will replace Judge David Stras, who was appointed to the Eighth Circuit Court of Appeals by President Donald Trump.

Thissen’s appointment means the seven-member state high court will include five Dayton appointees. In addition to his political service, Thissen, 51, is currently senior counsel for the Health Law Group at the Ballard Spahr law firm.

“He combined a brilliant legal mind, the highest integrity, and a special understanding of Minnesota from his 16 years of service in the Minnesota House of Representatives and his extensive travel throughout our state,” Dayton said Tuesday, explaining why Thissen stood out among the nominees.

At a news conference with Dayton, Thissen said he would cast no more votes as a state representative and planned to resign his seat on Friday. Dayton said he would not call a special election to replace Thissen, meaning his southwest Minneapolis House seat will be vacant until after the November election.

“I am now ready to move from policymaking to principled interpretation of the law,” Thissen said.

He is not the first legislator to transition from lawmaking to the state Supreme Court, but his shift from the House to the court in the middle of his term is unusual.

The court could consider cases related to issues he advocated for or against at the Legislature. Thissen said he would consider such circumstances on a case-by-case basis and follow staff advice about potential conflicts of interest.

Seventeen other former legislators have served on the court, most recently Kathleen Blatz, who was a justice from 1996 to 2006, and was chief justice for most of that period.

“I drew many, many times on my legislative experience,” Blatz said Tuesday. “It really deepened my appreciation for the three distinct branches of government and what that means, and sometimes it’s implicated in cases.”

Thissen was the leader of the House DFL Caucus from 2011 until the end of 2016. He served one term as speaker in 2013 and 2014, at a time when Dayton and the DFL had full control of state government; they worked together to pass income tax increases on high earners, a state minimum-wage increase and same-sex marriage legislation.

In his cover letter for the associate justice position, Thissen said that as a legislator he dug into a range of legal issues, and worked with communities to tackle local issues. “I’m inspired by the potential to make our obligations to each other under the law clearer and justice more accessible for Minnesotans,” he wrote. “I want to be a Minnesota Supreme Court justice to make sure that our judicial system always sees and never forgets the real people behind the litigation.”

As House speaker, Thissen was regarded by colleagues as coolheaded, intellectual and invested in the policy work. He wasn’t flashy, but was willing to diverge from Dayton and the Senate on some issues, such as how best to tax high earners and how hard to push for same-sex marriage.

“Paul Thissen is brilliant, compassionate, and dedicated to making Minnesota a better place for each and every resident,” House Minority Leader Melissa Hortman, DFL-Brooklyn Park, said in a statement. “I’m certain that with his commitment to law and justice, he will serve the state well on the Minnesota Supreme Court.”

Thissen made unsuccessful bids for governor in 2010 and again earlier this year. He announced in January that he would not seek re-election for his legislative seat, and a number of candidates entered the race to replace him in the DFL stronghold. DFL activists in April endorsed Jamie Long, deputy chief of staff to U.S. Rep. Keith Ellison.

A Bloomington native, Thissen is the father of three teenagers and is married to Karen Wilson Thissen, who is executive vice president and general counsel at Ameriprise Financial. He earned his undergraduate degree from Harvard and his law degree from the University of Chicago.

At Ballard Spahr, he has focused on health care transactions and regulations. He helps hospitals, clinics, group home facilities and other health care organizations navigate “complex regulatory regimes to complete deals,” Thissen said in his application for the post.

He started his law career as a clerk for Appeals Court Judge James B. Loken. Loken, who was nominated to the appeals court post by President George H.W. Bush, said he has watched his former law clerk’s career progress, and thinks Thissen will bring a balanced approach to the bench.

His background helps him understand there are two sides to legal and political arguments, and the importance of searching for consensus to work through problems, Loken said.

Thissen was one of four finalists for the state Supreme Court job, along with three current judges: District Court Judge Jeffrey Bryan, Minnesota Tax Court Chief Judge Bradford Delapena and Minnesota Court of Appeals Judge Lucinda Jesson.