In a DWI investigation, what percentage of blood alcohol is considered prima facie evidence of intoxication?

In the context of a DWI (Driving While Intoxicated) investigation, a blood alcohol concentration (BAC) of eight-tenths of one percent (0.08%) is established as the legal threshold for intoxication in Missouri and many other states. This specific percentage serves as prima facie evidence that an individual is legally impaired, meaning that it is sufficient by itself to support a legal presumption of intoxication without the need for further evidence.

This standard is derived from the legal framework governing impaired driving, which reflects both scientific studies on the effects of alcohol on driving ability and social policy aimed at reducing alcohol-related accidents. A BAC at or above this level indicates that an individual has consumed enough alcohol to impair their capacity to operate a vehicle safely.

Understanding this threshold is crucial for law enforcement and legal professionals involved in DWI cases as it guides their decisions during investigations and prosecutions.