Driving Under the Influence of Drugs: Mandatory Blood Test at the Driver's Request

In a judgment dated 15 October 2024, the Criminal Division of the French Court of Cassation held that the failure to carry out a blood test after a driver had reserved such a right—following a saliva test that returned positive for narcotics—irreversibly undermines the driver's right to request a technical examination or expert assessment.

Under the French Highway Code, when a saliva test is conducted by a police officer or judicial police officer to determine whether a driver has consumed substances or plants classified as narcotics, the officer must ask the driver whether they wish to reserve the right to a technical examination or expert assessment.

If the driver answers in the affirmative, a blood test must be performed without delay.

Failure to comply constitutes an irreparable infringement of the driver's rights and renders the procedure unlawful.