By Donna Lieberman — Earlier this spring, a 12-year-old Brooklyn girl made a devastating decision – she took her own life.

According to news reports, Maria Herrera, a sixth grader at Public School 72, was the subject of her classmates’ constant harassment. The little girl’s mother complained to the school, teachers and the Department of Education more than 20 times. Even after Maria’s classmates cut off her hair, nothing was ever done to protect her.

This heartbreaking tale of a beautiful child’s life cut short and an anguished family left to pick up the pieces serves as a painful reminder of the impact harassment can have on a young life. Tragedies such as this are exactly why the City Council passed the Dignity in All Schools Act (DASA) in 2004 – our officials wanted to try to limit the kind of suffering that led to Maria’s death.

DASA was supposed to establish strong anti-harassment policies in school. The law as written prohibits harassment, mandates training programs for school staff and creates a complaint process mechanism. DASA requires the tracking of harassment so that each time Maria’s mother made a complaint, a warning flag should have gone up that there was a problem in the little girl’s school.

But there were no warning flags. In fact, the DOE issued a statement saying there was no record of any harassment at all. Why? Because for four years, Mayor Bloomberg and schools’ Chancellor Joel Klein have completely disregarded their obligation to enforce the law.

By flouting DASA, the mayor and DOE have left our most at risk children open to pain and anguish that prevents them from being successful students – and jeopardizes their health and well being. School harassment is an urgent issue: Nationally, 65 percent of teens report that they have been harassed or assaulted during the past year because of their appearance, gender, sexual orientation, ethnicity, race, disability, gender expression or religion.

It is time for the mayor to act. Let’s learn from Maria’s tragic death. Every student deserves to feel safe in school. Our children deserve the chance to reach their full potential.

Donna Lieberman is the executive director of the New York Civil Liberties Union.