What must the State prove?
In a case of driving under the influence of liquor, the state must prove that the accused drove a vehicle on a public road while under the influence, or while the alcohol content of the accused’s blood exceeded 0,05g per 100ml. When these elements have been established, a court will consider the following factors in imposing sentence:
– the degree to which a motorist was under the influence of liquor;
– the extent to which his or her ability to drive was affected;
– traffic conditions at the relevant time;
– the type of vehicle being driven;
– the actual harm or danger caused by his or her driving;
– the time and place of the offence;
– whether the accused is a first offender.
Evidence against the accused may be given by the police, the examining doctor or any person who, at the time of the alleged offence, thought the accused was under the influence. The opinions expressed in court must be qualified by reasons. For instance, the statement ‘I believe he was under the influence’ is not acceptable evidence, unless it is followed by an observation such as ‘because he smelt strongly of liquor and his speech was slurred’.
[Source] South African Legal Advice