Forensic evaluation of alcoholic intoxication: legislation and practical aspects

Abstract

After a crash between a car and a motorcycle, without any fatal victims, the driver of the car was referred by the police for blood alcohol screening, as witnesses reported that he ran a red light. He was 37 years old at the time, reported no previous illness and that he had drunk three cans of beer and two shots of cognac two hours before being evaluated by the medical examiner. The physical exam revealed ataxia index-index, alcohol on breath and head congestion, but no altered neurological or psychological mental status. After consent, a blood sample was collected, which resulted in a blood alcohol content (BAC) of a 2.8 g/L. According to the scientific literature, anyone with such BAC would exhibit inability to stand and walk, disorientation, confusion and drowsiness. This case challenges the correlation between blood alcohol levels and the effectiveness of certain physical responses, and exemplifies how difficult it is for the appointed medical examiner to provide judicial and police authorities with a clinical diagnosis of a suspect BAC greater than or equal to 0.6 g/L, under the requirements of Law 11.705/08 (“Lei Seca”). According to current legislation, only the results of the BAC and the breath alcohol concentration are accepted for purposes of criminal prosecution. However, the legality of other means of evidence to attest drunkenness is on trial in the Supreme Court, being the expert clinical examination the emphasis of the discussion, since the evidence produced would meet for obtaining evidence of materiality to bring criminal action. The medical-legal elements that can be used in clinical examination and other forms of verification of acute intoxication by ingestion of ethyl alcohol are disussed based on the scientific literature.