The largest courtroom in the St. Tammany Justice Center, normally used for misdemeanor court, was packed with well-wishers and state and local officeholders Monday morning as Warren Montgomery was sworn in as district attorney for the 22nd Judicial District by retired state Supreme Court Justice Harry Lemmon.

Montgomery, who takes charge of an office that was run for three decades by Walter Reed, told those in attendance that he, like others who have sought office in the criminal justice system, is motivated by a thirst for justice.

“Unfortunately, we have to run for public office to see justice done, but you don’t want politics in the justice system,” said Montgomery, who previously ran an unsuccessful campaign for judge.

“The voters really spoke in this election that they wanted a justice system focused on justice and not on politics,” he said, drawing applause.

His goal, he said, is to run the office based on merit and hard work, calling that the American dream.

Lemmon administered the oath of office as Montgomery’s mother, Anne, held the Bible. The crowd gave the new DA a stranding ovation.

U.S. Sen. Bill Cassidy, R-La., who delivered the keynote address, said he has known the new DA for 40 years. They met when Montgomery, then a freshman at LSU, came to Cassidy’s high school to start a Young Life program, part of a religious organization for students.

Cassidy praised Montgomery as a person of faith and experience.

“He is a man who understands that all of us must have a standing before the law that is not built upon a personal relationship but is built upon the woman of justice wearing a blindfold,” Cassidy said.

The campaign to replace Reed, who left office after five terms under the cloud of a federal investigation, was contentious, and the sheriffs in both St. Tammany and Washington parishes backed Montgomery’s opponent in the runoff, Brian Trainor.

On Monday, the new DA made a point of reaching out to other elected officials.

“The truth is, we’re all in this together,” Montgomery said. “Everyone who goes to jail, unless they are there for the rest of their life, is going to come out of jail.”

He stressed the need to help offenders turn their lives around and praised efforts along those lines, like specialty courts.

The goal, he said, is simply to stop crime and help people: “That’s what it’s all about, not statistics but results in the lives of people. ... We can’t let politics be something that holds us back from achieving results.”

The brief ceremony, which also included Montgomery swearing in his top three staffers, was followed by a reception outside the DA’s office on the second floor. Portraits of Reed and his staff were gone from the walls inside the office, and Montgomery’s name gleamed in gold lettering on the glass front.

The mood in the courthouse was celebratory, as defense attorneys in attendance talked positively about the new administration and others noted that the occasion was a historic one.

Washington Parish Sheriff Randy Seal and St. Tammany Parish Sheriff Jack Strain were among many public officials at the festivities, and they sounded upbeat. Seal said he was encouraged by Montgomery’s speech and excited about working with him, calling his taking office a great thing for both parishes.

Strain described the new DA as “adamant” about making sure that the criminal justice system works and said that whatever bar Montgomery sets in terms of evidence, his deputies will meet it.

Civil rights organizer Belinda Parker Brown, who actively campaigned for Montgomery, said his election is “just the beginning” of reform and that her organization, Louisiana United International, will review cases prosecuted under Reed where they believe defendants were not treated fairly.

St. Tammany Parish Councilman Reid Falconer took note of the buzz in the courthouse. “A new wind is blowing in the parish, and it’s a good wind,” he said. “A wind of change.”

Follow Sara Pagones on Twitter, @spagonesadvocat.