Although the police cannot stop drivers randomly to check for drunk driving, they can stop them on suspicion of violating any traffic law or detain them at a properly established sobriety checkpoint, even when there is no suspicion of drunk driving. Once drivers are stopped, they can be subjected to field sobriety tests on the slightest suspicion of alcohol consumption or can be required to submit to a preliminary breath test even when there is no suspicion of alcohol consumption. If probable cause surfaces from these investigations, a driver can be arrested. A driver's cooperation in providing a breath sample for use in later criminal prosecution will be 'encouraged' by threat of license suspension for refusal. If the driver passes the breath test, he/she will probably be released. If the driver fails the test, his/her license can be seized on the spot. Few drunk-driving defendants contest their guilt, in part because most of the sanctions can be applied administratively, regardless of whether they are convicted. Many States now limit plea bargaining in drunk-driving cases. In processing drunk-driving cases, the criminal justice system essentially functions as a guilt-stamping machine.