Drugs behind the wheel: what needs to be proven in the case file

In a drug driving case, Article 336(2) of the Criminal Code punishes driving a vehicle for which a driver’s license is required by a person under the influence of psychoactive substances. In Decision no. 25/2025, the High Court determined that both the presence of the psychoactive substance in biological the evidence and its ability to affect the ability to drive must be established.

The decision does not require proof of a concrete change in behavior or a visible impairment at the wheel. The legal question is whether the substance identified had the ability to cause such impairment. Therefore, mere mention of a positive screening test should not be confused with a complete analysis of the biological evidence and its medico-legal relevance.

Drugs behind the wheel: what technical evidence matter

Depending on the case, we can rely on the test and collection protocols, laboratory documents, the identity of the substance, the results of the biological samples, the sequence and timing of the collection, as well as the medico-legal explanation regarding the possible effects of the substance. The defense can examine whether the evidence were obtained and interpreted correctly and whether the conclusions meet the standard established by the Supreme Court.

The Code of Criminal Procedure allows the ordering of an expert opinion when an expert’s opinion is necessary to clarify important circumstances. The request must indicate the facts and technical questions that need to be clarified. If the report is incomplete or the conclusions are unclear or contradictory, the law provides for means of completing or conducting a new expert opinion, under the applicable conditions.

What an expert report can entail

  • identification of the psychoactive substance and the results of the biological evidence;
  • the forensic interpretation of the result in relation to the time of the conduct;
  • clarification of the substance’s ability to affect the ability to drive;
  • the explanation of the limits and degree of certainty of the technical conclusions;
  • clarifying any inconsistencies between the documents, analyses and the expert report.

The objectives must be adapted to the documents in the case file. An expert opinion does not guarantee a favorable solution, and the court assesses the entire body of evidence, not just a single isolated result.

Practical steps for defense

  1. Request access to the testing, harvesting, and analysis documents in the file.
  2. It records the chronology of the stop in traffic, the testing and collection of biological samples.
  3. Discuss with the lawyer if an expert opinion is necessary and formulate precise technical questions.
  4. Check if the report addresses the identified substance and its ability to affect driving ability.
  5. He contests the unclearities or contradictions punctually, through the applicable procedural means.

Official sources

For articles and information about criminal defense, consult page dedicated to criminal law. The information is general; the classification and strategy depend on the evidence and the circumstances of each case.