Highway Code

Sentence 10/2026: Driving under the influence of drugs, new thresholds and urgent regulations

The Constitutional Court redefines the criteria for driving under the influence of drugs, requiring clear parameters and legislative intervention to ensure certainty and protection.

by Guido Camera, Stefano D'Errico* and Elio Santangelo*

6 March 2026

3' min read

Translated by AI

Versione italiana

3' min read

Translated by AI

Versione italiana

With the sentence 10/2026, the Constitutional Court ruled that it is no longer necessary to ascertain the driver's state of psychophysical alteration in order to drive after taking drugs or psychotropic substances (commonly known as drugs, even if they include medicines). However, the mere chronological succession between consumption and driving behaviour is not sufficient: it is necessary to verify, at a time close to driving, the presence in the biological liquids of substances which, by quality and quantity, are scientifically capable of determining, in an average user, an alteration of the ability to control the vehicle and, therefore, a condition of greater danger.

The Court thus saved the 2024 reform of Article 187 of the Road Code by delimiting its scope. The repressive automatism based on toxicological positivity alone is excluded; the new evidential centre of gravity is the scientific significance of the biological data.

The limit of the sentence

The driver, the judgment notes, 'will know that he must abstain' from driving until the effect of the substance can reasonably be said to have ceased. But that moment may be difficult to pinpoint, with non-negligible margins of uncertainty particularly in the course ofcontinuing treatment, with no guarantee as to the outcome of any (potentially still positive) toxicological test and legal consequences.

The shift of the pivot to quality and quantity of the substance detected points to the need for alegislative intervention of technical adaptation.

The 'narcotic or psychotropic substances' listed in the regulations include both those whose use is considered illicit and psychoactive drugs regularly prescribed for therapeutic purposes. The tabular system annexed to Presidential Decree 309/1990 is constantly updated by ministerial decrees and now includes many substances. If punishability depends on the quantitative and qualitative significance of the biological data, it seems consistent that the legislator should identify explicit regulatory parameters and methodologies for determining the thresholds of relevance, based on transparent and updatable criteria.

Punishment thresholds

Comparative experience shows that, in systems that have addressed the same problem, the determination ofthreshold values for specific substances has been deemed necessary to ensure certainty of application. It remains evident that the identification and applicability of such values are linked to the available scientific knowledge. The comparison does not offer a single model, but highlights a common need: when punishability is anchored to qualitative-quantitative data, these must be made explicit and normatively regulated.

The Problem of Medicines

The issue is particularly relevant in the case of prescribed medicines. The legislation does not distinguish between the taking of illicit substances and the use of psychoactive drugs, nor does it automatically provide for the exclusion of punishability in the presence of duly authorised treatment. A possible line of legislative intervention could therefore consist in introducing a non-punishability clause or a differentiated regulation for therapeutic use that complies with a prescription. At least in cases where there has been a prior judgement of fitness to drive expressed by the local medical commission, thus coordinating criminal liability and health assessment.

In such a scenario, in fact, the driver complies with a technical-health assessment made by a public body delegated precisely to verify the compatibility between health conditions, current treatment and ability to drive.

Assessment and clinical judgement

Still from the medico-legal point of view it should be noted that the ministerial circular of 11 April 2025 does not offer fully defined criteria for formulating a conclusive clinical judgement integrated with the toxicological assessment. In accidents with injured persons, moreover, the ascertainment of the state of psychophysical alteration - which has remained a necessary requirement in cases of serious and very serious road injuries and road homicide - may not be ordered in good time.

It may happen whenever, on the basis of the initial prognosis, the event appears to be minor. If the prognosis then worsens, the absence of an immediate clinical and toxicological assessment may result in a significant loss of relevant evidence. The possible lack or tardiness of the assessment may therefore have a decisive impact on the reconstruction of responsibility.

The route to take

To consolidate the balance outlined by the Court, a coherent legislative intervention should therefore provide for:

determination of cutoff values for substances related to Presidential Decree 309/1990, with mechanisms for technical-scientific updating;
a specific discipline for therapeutic use in compliance with medical prescriptions, capable of coordinating criminal liability and health assessment;
a standardisation of clinical-laboratory assessments for medico-legal purposes.

Only with a regulatory framework that makes the scientific and applicative parameters explicit and consistent will it be possible to realise the path traced by the Consulta. In criminal matters, safety protection is all the more effective the more the rule is clear, predictable and uniformly applicable.

*Complex Unit (Uco) Forensic Medicine, Giuliano Isontina University Health Authority