It seems like a new teachers contract was agreed just yesterday – it was actually back in October – but already efforts are underway to water it down. Consider a City Council hearing yesterday in which several teachers, including the president of the United Federation of Teachers, Randi Weingarten, testified about the need for broad new protections for “whistleblowers” in the Department of Education.

The teachers and their friends on the City Council argue that current whistleblower protections are inadequate for some of the situations that face teachers. Ms. Weingarten testified about cases of alleged reprisals against teachers who called attention to grade inflation or health and safety violations. “We rely on school-based educators to be the eyes and ears of parents and the public who don’t have full access to schools,” Ms. Weingarten told the education committee. “These educators need to know that they can advocate on behalf of children and families without putting their careers at risk.”

No doubt. The proposed law, however, strikes us as an illogical way to deal with the problem. It is crafted so broadly that teachers effectively could gain job security not just by complaining about serious problems (those com plaints are already protected by current whistleblower laws) but by raising the alarm about any policy they found objectionable. In theory, a mediocre teacher on the verge of being fired could win tenure by blowing the whistle on a reading curriculum or the scheduling of bathroom breaks or the mandate that teachers do hall monitor duty, a requirement of the recent contract. The proposed law would also make it possible for teachers to sue the Department of Education themselves to correct “problems” even if a lengthy investigation had already determined that the complaint was frivolous.

Union leaders are right when they say that there are a lot of problems in the city schools, but New Yorkers are starting to wonder whether teachers are always the best people to spot those problems and whether an overly generous new whistleblower law is the best way to bring those problems to light. Teachers are not the only people intimately involved in education. What about parents? They often know as much as or even more than the teachers. The single best whistleblower statute for the schools would be a voucher law that would allow poor parents the same education choices as rich parents. That will do more than a complaining teacher to solve the problem.