Zero Tolerance refers to an approach to criminal justice advocated by Right Realists and associated with James Q Wilson's Broken Windows Theory. It is an approach that has been used in parts of the US and (to a lesser extent) the UK with disputed levels of success, The idea is that low-level crime should not be tolerated and severe penalties should be in place for anti-social behaviour and minor incivilities in order to deter more serious crime and ensure that collective conscience and social solidarity is maintained by clear boundary maintenance. However, critics say that control is achieved at the expense of justice with people serving long sentences for minor crimes and the discretion that police inevitably use often being wielded in a discriminatory manner, perhaps because of institutional racism.