[How relevant is the risk of losing evidence due to delayed blood sampling? Conclusions from the evaluation of blood analysis results].

If the order of a judge to take a blood sample can only be obtained with a marked delay after the incident, evidence proving that a suspect had been driving under the influence of alcohol or drugs of abuse may be lost. The evaluation of blood analysis results from the Institute of Legal Medicine in Frankfurt/Main from the years 2012-2014 shows that in 1.6 to 11.6% of positive cases, the drug concentrations were near the legal limits (20.2% of alcohol-positive and 7.5% of illicit drugs-positive samples). A loss of evidence can thus be expected in a large number of cases when the time between the police check of a driver and the collection of a blood sample increases. Blood concentrations of alcohol and drugs of abuse, especially tetrahydrocannabinol, cocaine, methamphetamine, and morphine, may already have dropped significantly after a delay of only half an hour. These delays are typically due to the time elapsing until the order to take a blood sample has been obtained from a judge and a medical doctor becomes available and arrives at the police station to draw a blood sample. The recommendation of medicolegal experts is to keep the time between police check of a suspect and blood sampling as short as possible. In routine cases, a realistic maximum of one hour should not be exceeded.