Howard Edelman isn’t well known in the education community. He should be: He has unilateral authority to change how the city Department of Education spends millions of dollars and the way principals choose to staff their schools. He has a dramatic impact on the lives of students.

Edelman is an arbitrator. When DOE moves to terminate a teacher for misconduct or incompetence, he decides whether the teacher stays or goes. And, if it’s “stay,” what the penalty should be.

Like his fellow arbitrators, Edelman’s judgment is final. (The city can appeal in court, but judges are loath to overturn arbitration decisions.)

And, like too many other arbitrators, Edelman makes it a priority to find ways to keep teachers in classrooms, with little apparent consideration of the impact on schools or students.

This is most evident, and troubling, in sexual misconduct cases.

In a breakthrough 2005 agreement, the union and DOE inserted language into the teachers contract stipulating “a mandatory penalty of discharge” to any union member “found by a hearing officer to have engaged in sexual misconduct.”

The contract defined sexual misconduct as including: “sexual touching, serious or repeated verbal abuse (as defined in Chancellor’s Regulations) of a sexual nature, action that could reasonably be interpreted as soliciting a sexual relationship, possession or use of illegal child pornography” as well as action that constitutes criminal conduct.

Union leaders often call this a “zero tolerance” policy. Problem is, Howard Edelman and his colleagues won’t enforce it. They repeatedly find that some sexual conduct by teachers is permissible.

In 2008, Edelman found that a teacher who rubbed the back and neck of a student in an empty classroom while speaking in threatening sexual innuendo — “I can make you do things you don’t want to do” — should get a mere two-month fine. The teacher had twice before been cited for improper touching.

Edelman’s terse rationale: “A teacher rubbed a student’s back. He did not have sex with the student or ask the student to have sex with him.”

In 2010, Edelman found that another serial abuser should be returned to the classroom after touching the bare shoulders and neck of a student while telling her she could strip for him.

The teacher “was not really soliciting sex from but was engaging in sexual banter,” with the student, he found — even though there is no precedent or protection in the contract for “sexual banter.”

He also found a way to forgive the use of child porn, calling a teacher’s secret agreement to be sent nude photos of a student “a lapse in judgment . . . [that] does not justify upholding his termination, I am convinced.” The contract explicitly says otherwise.

Yet Edelman is no anomaly. Many other arbitrators normalize sexual behavior or invent standards to arrive at decisions that flout zero tolerance.

Paul Zonderman has leniently arbitrated many misconduct cases. In one, he found that a special-education teacher touched boys so often that his actions “at worst, suggest pedophilia.” Yet Zonderman ordered nothing more than a reprimand.

Eric Lawson found that a Manhattan 6th-grade teacher repeatedly hugged female students, touched a student’s breast and leg and made sexually suggestive remarks to several students. He described the teacher as “unrepentant, claiming to be a victim” and said he didn’t deserve to keep his job “as long as he insists upon his innocence.”

Yet Lawson sent him back to the classroom anyway, ordering a six-month suspension and mandatory therapy.

In a distasteful recent case, a Bronx high-school teacher repeatedly called a large-breasted student “watermelon girl” and told her, if he felt she was dressed inappropriately, to “put your melons away” and “cover up your melons.” He called other female students “Wonder Woman,” “Chocolate Girl,” and “Dark Chocolate,” purportedly to encourage them. There is no evidence that he used nicknames to encourage male students.

The arbitrator, John Woods, said the teacher’s “unwelcome communication of a sexual nature is prohibited. However, termination is not the appropriate penalty in this case.” In fact, prohibited sexual communications require termination under the contract. Yet Woods ordered a penalty of just a week without pay.

With these and other arbitrators minimizing the sexual behavior of accused teachers with their students, the DOE has had little success in terminating teachers accused of violating the 2005 provision. Only about a quarter of those for whom probable cause of sexual misconduct has been found have lost their jobs.

In the other cases, an arbitrator has sided with a serial molester over the isolated, terrified child he threatens. And with a profane, sexualizing bully over the child he singles out as “watermelon girl.”

The union needs to stop claiming there’s a zero-tolerance policy for teacher sexual abuse. The arbitrators disagree.

Campbell Brown is the founder of the Parents Transparency Project and a former anchor for NBC and CNN.