For example,  Federal and state regulations also require drug and alcohol testing. These regulations apply to all truck drivers who must carry a commercial driver license(CDL). The tests identify alcohol, marijauna, cocaine, opiates amphetamines, and PCP in the body.These tests fall into four categories: pre-employment, reasonable suspicion, random drug tests, and post-accident tests. Enforcement of these tests falls within the purview of a designated employer representative who must be appointed by the employer. Drivers are only permitted to perform safety duties if they return a negative result on a pre-employment test. Trucking companies must also research the drug and alcohol testing history which includes records from prior employers. As to reasonable suspicion, if the company suspects drugs or alcohol use, it must test that driver. In addition, random tests are performed under an acceptable scientific method without notice to the driver. After an accident, testing is required. It would also apply when a driver is cited for a moving violation that includes  either  towing at the scene or that involves required medical care away from the scene. A police officer may require an alcohol or drug test if he suspects impaired driving. This can be accomplished by either breath, blood, or a urine test. The amount of alcohol impairment is lower than for non-commercial vehicles. A prior OVI conviction can be used as evidence in a civil case for personal injuries to show negligence and negligence per se.