Are zero tolerance policies effective in the schools?: An evidentiary review and recommendations.

Narrative evidentiary review of roughly two decades of zero-tolerance practice in US schools

US K-12.

A commissioned expert task-force review rather than a quantitative synthesis, so it is graded C - it aggregates a literature without pooling it and without a risk-of-bias screen. Its value is as the discipline field's own adversarial pass on its dominant policy, conducted by a body with no stake in the outcome.

After roughly twenty years of implementation the task force found "surprisingly few data that could directly test the assumptions of a zero tolerance approach to school discipline, and the data that are available tend to contradict those assumptions." Zero tolerance was judged not to have made schools safer without limiting learning opportunities, not to reflect what is known about adolescent development, and to have driven excessive juvenile-justice referrals. The general conclusion: the policy's premises were never evidenced and the available evidence runs against them.

Not applicable — a policy review rather than a child-outcome estimate.

The quantitative work that followed agrees. Curran 2016 finds state zero-tolerance laws raised suspension rates by 0.5 pp with no improvement in principal-perceived behaviour, and Bacher-Hicks et al. 2024 find strict-discipline schools raise adult arrest and incarceration by 15-20%.