Teacher tenure discussions often suggest that what is in the best interest of teachers is also in the best interest of students. But the groundbreaking decision in the Vergara case makes it clear that early, and effectively irreversible, decisions about teacher tenure have real costs for students and ultimately all of society.

Teacher tenure, and the related onerous and costly requirements for dismissing an ineffective teacher, have evolved into a system that almost completely insulates teachers from review, evaluation, or personnel decisions that would threaten their lifetime employment. Researchshows that this results in serious harm both to individual students and to society, because a small number of grossly ineffective teachers are retained in our schools.

The California court, noting that education is a fundamental right of California youth, struck down the law that requires administrators to make essentially lifetime decisions after a teacher has been in the classroom for just 16 months and has yet to complete an induction program. Similarly rejected were statutes that make requirements for removing a tenured teacher so onerous and costly that it is seldom attempted.

Legislatures will likely respond to the court decision by lessening (but not eliminating completely) the burden of dismissing an ineffective teacher. The teachers unions will undoubtedly claim that is an attack on teachers. It is not. It is simply an attempt to restore some balance in the system.

A small percentage of teachers inflicts disproportionate harm on children. Each year a grossly ineffective teacher continues in the classroom reduces the future earnings of the class by thousands of dollars by dramatically lowering the college chances and employment opportunities of students.

There is also a national impact. The future economic well being of the United States is entirely dependent on the skills of our population. Replacing the poorest performing 5 to 8 percent of teachers with an average teacher would, by my calculations, yield improved productivity and growth that amounts to trillions of dollars.

The teachers unions have an opportunity to participate in crafting a more balanced system that promotes world-class schools. By not collaborating, they face the very real possibility that courts and state legislatures will continue to disregard their voices in attempting to improve schooling opportunities. The stakes in getting it right are extraordinarily high.

-Eric Hanushek

Eric Hanushek is an economist and senior fellow at the Hoover Institution of Stanford University. He is co-author of “Endangering Prosperity: A Global View of the American School.” He testified for the plaintiffs in the Vergara case.

This first appeared on the New York Times’ Room for Debate page.