School zero tolerance policies spread in the 1990s. The federal Gun-Free Schools Act of 1994 required a one-year expulsion for bringing a firearm to school. Many districts extended mandatory punishments to fights, drugs, dress code violations and defiance.
An American Psychological Association task force concluded in 2008 that zero tolerance had not made schools safer. Discipline is also unequal. In the 2021–22 school year, Black boys were 8 percent of K-12 students but 22 percent of students who received an out-of-school suspension, according to federal civil rights data. Students who are suspended are more likely to fall behind, drop out and enter the juvenile system.
The term also names federal immigration policy. In 2018, the Justice Department's zero tolerance policy prosecuted every adult caught crossing the border illegally, which led to thousands of family separations.