A preliminary test applied by a uniformed police officer by means of a breathalyser to a driver whom he suspects has alcohol in his body in excess of the legal limit, has committed a traffic offence while the car was moving, or has driven a motor vehicle involved in an accident. The test may be administered on the spot to someone either actually driving, attempting to drive, or in charge of a motor vehicle on a road or public place or suspected by the police officer of having done so in the above circumstances. If the test proves positive (see drunken driving), the police officer may arrest the suspect without a warrant and take him to a police station, where further investigations may take place (see specimen of breath). It is an offence to refuse to submit to a breath test unless there is some reasonable excuse (usually a medical reason), and a police officer may arrest without warrant anyone who refuses the test. The offence is punishable by a fine, endorsement (carrying 4 points under the totting-up system), and discretionary disqualification. A police officer has the power to enter any place in order to apply the breath test to someone he suspects of having been involved in an accident in which someone else was injured or to arrest someone who refused the test or whose test was positive.