The Hennepin County judge running the trial of ex-Minneapolis police officer Derek Chauvin in the death of George Floyd is facing the biggest test yet of his long legal career.

In addition to his 14 years on the bench, Judge Peter Cahill's nearly four-decade career includes stretches for the prosecution, the defense and as an administrator, notably as chief judge, and as the top deputy to Amy Klobuchar during her tenure as county attorney.

For the next month, Cahill will sit behind a coronavirus protection shield on the 18th floor of the downtown Minneapolis courthouse presiding over the most widely viewed and closely scrutinized trial in state history.

"This moment is not too big for him," said Chief Hennepin District Judge Toddrick Barnette, who hand-picked Cahill to oversee the trial. "He will make thoughtful legal decisions based upon the law, even if the decisions are unpopular."

Because of Cahill's groundbreaking order to livestream the trial, the proceedings are available on the internet to the world. A big part of Cahill's job will be to keep widespread chaos, anger and criticism about Floyd's death out of the courtroom so Chauvin can get a fair trial. In August, he is scheduled to do it again for the trial of the three other fired Minneapolis cops accused of aiding and abetting Chauvin.

Long before Republican Gov. Tim Pawlenty put Cahill on the bench, he was an influential player in Hennepin County courts as the trusted confidant to Klobuchar, who is now the state's senior U.S. senator. He became a judge in 2007, the same year she was sworn in to the U.S. Senate.

His connections to big legal names began in law school at the University of Minnesota working as a clerk to Michael Colich, who has been a top criminal defense attorney for decades.

"He was always very confident in himself and he was extremely smart," Colich said. "I learned very quickly how he handled himself in the courtroom. He was a tremendous trial attorney."

Cahill, 62, graduated from law school in 1984, then went to work as an assistant public defender in Hennepin County for three years before joining Colich's private defense firm. Six years later, Cahill opened his own practice, which he ran until 1997 when he became an assistant prosecutor of violent crimes for the County Attorney's Office.

Earlier this year, Colich said he represented a client in front of his former clerk. "He treats everyone the same. He's very respectful, but you know who's in charge," Colich said.

Retired Judge Kevin Burke said Cahill's diverse experience matters. "He did serious cases. He understands the courtroom and the role that both sides have. That's a really good background to have for a series of cases like this," Burke said.

Cahill declined to be interviewed for this story.

Cahill's trial management skills in Chauvin's case have been tested by outside developments and requests for delays.

He denied multiple challenges from state Attorney General Keith Ellison who fought Cahill's order to livestream the trial — a first for Minnesota. Ellison argued in a motion that witnesses "should not be forced to sacrifice their privacy or suffer possible threats of intimidation when they perform their civic duty and testify." He also argued that Cahill's order sets a wider precedent that could require the broadcasting of all high-profile criminal trials.

The judge didn't back down from his order that said space constraints because of the coronavirus pandemic and the massive public interest in the case necessitated the broadcast.

A month before jury selection started, the New York Times published a story saying that Chauvin had agreed to plead guilty to third-degree murder last summer before then-Attorney General William Barr quashed it. A couple of weeks later, the Star Tribune reported that a federal grand jury was convening to consider civil rights charges against Chauvin.

Just as jury selection was to begin in early March, there was back-and-forth with the state appellate courts over whether Cahill should reinstate a third-degree murder charge against Chauvin. Cahill had dismissed the charge last fall, saying it didn't apply, but the Court of Appeals disagreed and he was compelled to reinstate the charge, adding it to the second-degree murder and manslaughter charges facing the former officer.

Then, four days into jury selection, after seven jurors had been chosen, the city of Minneapolis dropped the bombshell of a record-setting payout of $27 million to Floyd's family. Cahill was forced to bring back the seated jurors to ask if they had heard the news. He ended up removing two jurors.

But he pushed ahead with selection and ended up with 15 seated jurors at midday Tuesday.

His courtroom style was on display during jury selection. He kept to a strict schedule. He was warm and friendly with jury candidates, direct, open and mostly cordial with everyone else.

One potential juror, who was not selected and said he was nervous about being in a courtroom for the first time, praised Cahill.

"I felt very positive about the entire process," said the man, who asked not to be identified, but who sells real estate. "Judge Cahill is extremely nice and made a person feel extremely comfortable."

Outside the courthouse, Cahill was photographed smiling, window rolled down, behind the wheel flashing a "hang loose" sign at the gaggle of news photographers waiting at the garage entrance. Arlo Guthrie's "Lightning Bar Blues" blasted from his car.

Inside the courtroom he is formal, but hints of his irreverent wit poked through. As jurors filed in one day, he said, "It's not like church, you can sit in the front row if you like."

Another time, defense attorney Eric Nelson's phone rang in court — an embarrassing faux pas. A chagrined Nelson apologized. Cahill responded, "I'm just glad it wasn't mine."

Former Hennepin County Chief Public Defender Mary Moriarty praised Cahill's gentle approach with jurors. "I think he was a good choice for this trial. Some judges would not have been," Moriarty said. "The stress of this trial has been astronomical."

He's occasionally shown flashes of temper. He threatened to kick out the media for sharing security details he said should not be public. He pointedly defended Nelson against complaints from a prosecutor. He has expressed his annoyance more than once about city leaders continuing to talk about the $27 million payout to Floyd's family.

Michael Brandt, a longtime Twin Cities criminal defense attorney who has appeared in front of Cahill many times, said he's generally even-keeled. "There's not a lot they could throw at him that he wouldn't handle with a certain aplomb and professionalism," Brandt said.

He also praised Cahill's sense of fairness. "One of the things that I admire about him is he really does give each side a chance to be heard and he's pleasant about it," Brandt said.

Cahill grew up the youngest of six just outside Milwaukee. His late father, Jerome Cahill, was a lawyer and prosecutor who was twice elected district attorney — once as a Democrat and once as a Republican.

The judge and his wife have four adult children. Cahill's wife was a longtime clerical supervisor in the office before retiring two years ago. Their son, Sean Cahill, is an assistant Hennepin County attorney who was previously a public defender.

As a young boy, Cahill attended St. Joseph School in Waukesha where his classmate Ralph Ramirez would go on to become a Waukesha County judge. "He's the only guy that beat me in the spelling bee in grade school," Ramirez said in an interview.

Ramirez said he was proud of Cahill's reaction when a prosecutor referred to the defendant as "Chauvin." Cahill cut off the lawyer, sharply advising him that the defendant, like everyone else in his courtroom, would be referred to with an honorific and called "Mr. Chauvin."

"He will control that courtroom and he will give both sides a fair trial," said Colich, his former mentor. "There's no question about that."

Rochelle Olson • 612-673-1747

Twitter: @rochelleolson