A common contributor to juvenile delinquency rates is a phenomenon referred to as the school to prison pipeline. In recent years, school disciplinary measures have become increasingly policed. In fact, 67% of high school students attend schools with police officers. This rise in police presence is often attributed to the implementation of zero tolerance policies. Based on the "broken windows" theory of criminology and the Gun-Free Schools Act, zero tolerance policies stress the use of specific, consistent, and harsh punishment to deal with in school infractions. Often measures such as suspension or expulsion are assigned to students who deviant regardless of the reason or past disciplinary history. This use of punishment often has been linked with increasing high school drop out rates and future arrests. It was found in a 2018 study that students who received a suspension were less likely to graduate and more likely to be arrested or on probation. As stated in research by Matthew Theriot, the increased police presence in school and use of tougher punishment methods leads student actions to be criminalized and in turn referred to juvenile justice systems.