Aaron Benner, a former St. Paul Public Schools teacher who was an outspoken critic of the district's student discipline policies, is suing the district, alleging it retaliated against him for his public stance.

The suit, filed Thursday in U.S. District Court, is based on claims dating to the 2014-15 school year — Benner's last with the district — when former Superintendent Valeria Silva still led St. Paul schools.

Silva since has been ousted, and Benner now is an administrator at Cretin-Derham Hall in St. Paul. But the city's human rights department concluded recently that there was probable cause to believe that racial discrimination and retaliation had occurred.

Benner was targeted in 2014-15 for four personnel investigations over a six-month period while he taught fourth grade at an East Side school.

After its investigation, the human rights department sought to mediate a settlement between Benner and the district, and to urge the district to correct its behavior. But the effort failed, leaving Benner to now press his case in court. He is seeking an unspecified amount of back pay plus damages for "mental anguish and suffering," the complaint states.

His attorney, Reid Goldetsky, declined to comment Thursday.

St. Paul schools spokeswoman Toya Stewart Downey said that the district does not comment on pending litigation.

Benner, who is black, has long argued that district concerns over the disproportionate percentage of black students being suspended has led to many students not being held accountable for misbehaving — setting them up for failure in the long run.

He took issue with the district's ties to Pacific Educational Group, a consultancy that advises "courageous conversations" around the subject of racial bias, and his public profile grew to include a June 2015 appearance on Fox News Channel's "The O'Reilly Factor."

That summer, Benner also shared with the Star Tribune the details of a stressful 2014-15 school year during which the 20-year teaching veteran — who until then had a clean disciplinary record — was subjected to a series of investigations by Lisa Gruenewald, principal of John A. Johnson Achievement Plus Elementary.

Benner said then that the district's actions were designed to silence him or to lay the groundwork to fire him, and that he was forced to pursue other opportunities due to fears he would be terminated.

A district official countered that the probes, while unusual in number, were not without cause or "retaliatory in any way." They now form the basis of the lawsuit filed Thursday.

In its investigation, the human rights department noted that in one case Benner was required to provide a doctor's note proving he was ill on a day when he called in sick. The department said no other teacher at John A. Johnson had been asked to do the same. The fact that Benner had no previous blemish in his work history only strengthened his claims that he was being retaliated against for his criticism of the district, the department's findings state.

On Thursday, Benner said: "This may be a surprise to many people, but at this time I have no comment."

Anthony Lonetree • 612-673-4109