Driving under the influence of drugs in the Netherlands: Toxicological results between 2017 and 2023

https://doi.org/10.1016/j.forsciint.2025.112782Get rights and content

Highlights

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    In the Netherlands, the main drug used by impaired drivers is cannabis.
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    Blood samples for impaired driving drug testing rose tenfold from 2017 to 2023.
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    Drug-impaired driving is prevalent mostly among younger male drivers.
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    14 % of suspected impaired drivers had used multiple drugs.
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    35 % of blood samples were negative, in spite of suspicion for impaired driving.

Abstract

This study evaluates the presence of drugs of abuse (DOA) in blood from drivers suspected of driving under the influence of drugs (DUID) in the Netherlands from 2017 to 2023. After the introduction of new Dutch DUID legislation in July 2017, police officers were provided roadside oral fluid drug testers to establish suspicion of DUID. Since, there has been a steady and continuing increase in the number of apprehended DUID drivers. A large set of 64,116 blood samples was analysed for the following DOA: cocaine, THC, morphine, GHB and Amphetamine Type Substances (ATS: amphetamine, methamphetamine, MDMA, MDA, and MDEA), and compared with the Dutch legal limits. Most of the apprehended drivers were men (92 %), with a median age of 29 years. Of the analyzed blood samples, 65 % was found positive for one or more DOA. The most prevalent drug was THC (71 %), followed by amphetamine type substances (ATS, 30 %), cocaine (15 %) and GHB (6.8 %). Poly-drug use was found in 14 % of the samples, main combinations being THC with amphetamine or cocaine, and GHB with amphetamine. Factors contributing to negative blood results are, amongst others, the blood-oral fluid ratio, a time delay between oral fluid testing and blood sample collection and sending in samples despite a negative oral fluid test. THC was more common amongst younger drivers (under 26 years old), whereas cocaine and ATS use increased with age. The study presents important knowledge for both policymakers and DUID prevention specialists.

Introduction

Impaired driving represents a significant and evolving threat to global road safety. While alcohol has traditionally been the primary concern in impaired driving, drug-related impairment has become increasingly recognized in recent decades. In the Netherlands, it has been estimated that 10 % of car crashes involve driving under the influence of drugs (DUID) [1], which is a significant risk.
The Dutch police employs a number of protocols to ensure effective enforcement against driving under the influence (DUI). Officers are allowed to apprehend drivers based on, for example, driving behavior, visible signs of alcohol or drug use and severe car crash involvement. While suspects can be tested for DUI of alcohol using breath alcohol analysis at the police station, the determination of DUID requires invasive blood sampling followed by toxicological analysis in a certified laboratory. The latter procedure is only authorized when sufficient suspicion of DUID has been established. A positive blood test can lead to significant legal consequences for the driver such as a fine, mandatory educational intervention, the revocation of driving license and/or a custodial sentence.
However, prior to 2017, Dutch police were hindered in enforcement due to limited DUID roadside testing tools as well as the absence of specific legislation. To establish suspicion of DUID, police was relying primarily on behavioral observations and field impairment testing such as the psychomotor test (PMT). The PMT is used to register signs of DUID, such as bloodshot eyes, slurred speech or tremors. One or more positive indicators justifies a subsequent DUID blood test.
In these earlier years, approximately 1000 DUID case samples were investigated at the Netherlands Forensic Institute annually on a population of approximately 10 million drivers.
The situation underwent a significant change in July 2017, following the implementation of new legislation within the Dutch Road Traffic Act (Article 8). Firstly, this amendment provided law enforcement authorities with roadside oral fluid drug testers as a preliminary DUID test. Police can now request a blood test after either a positive oral fluid test, a traditional PMT, or, for example, immediate confession or serious accident involvement.
Secondly, similar to alcohol, whole blood concentration limits were stated for the following drugs of abuse (DOA): cannabis (THC), cocaine, morphine, GHB, amphetamine, methamphetamine, MDMA, MDA and MDEA (see Table 1). This allowed for simpler interpretation of blood test results and enabled the upscaling of investigated DUID cases.
Per se limits for single use were specified based on risk of impaired driving. For novice drivers, a zero tolerance limit is applied (only) for alcohol. Since the combined use of different impairing substances is generally considered a greater danger for traffic safety and often leads to more severe penalties, zero tolerance limits were implemented for poly-drug use. Zero tolerance limits are based on analytical detection limits and their associated measurement uncertainty.
Specific rules were outlined for the Amphetamine Type Substances (ATS). Firstly, the presence of multiple ATS is considered as single use. Secondly, the sum of the concentrations of the individual ATS leads to a concentration for the group of ATS that has its own limit. Therefore, the presence of multiple ATS concentrations below the limit, may still lead to a violation of the DUID law.
The reporting limit is equal to the limit for poly-drug use for all substances; except for ATS where the reporting limit is 12 µg/L (See Table 1).
All DUI cases in the Netherlands during 6.5 years after implementation of this new legislation (July 2017 – December 2023) were examined for analytical findings and more in-depth analysis of trends. The focus was on the 64,116 cases in which only DOA (and no alcohol) were analyzed in blood of suspected drivers. The aim of the study was to evaluate the prevalence of the legislated DOA in suspected drivers in the Netherlands and to help assess current patterns of drug use in drivers.

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Section snippets

Selection of DUI cases

This study included all DUI cases of alcohol and drugs (as mentioned in the Dutch road traffic act) in the Netherlands in the period July 1st 2017 until December 31st 2023.
The oral fluid drug screening apparatus used was initially Dräger DrugCheck 3000 until March 2023, and from January 2023 Securetec DrugWipe 5S. Five different drugs or drug classes are tested: cocaine, opioids, amphetamine, methamphetamine/MDMA and cannabis. No specific selection test for GHB is currently available.
Police

Investigated DUI cases

Following the implementation of new DUI legislation in the Netherlands in July 2017, the total number of blood samples submitted for laboratory analysis increased tenfold over the subsequent six-year period and continues to increase.
The volume of analytical packages requested by law enforcement agencies for blood analysis (alcohol, drugs, or both) is presented in Table 2. Notably, the majority of requests (73 %) pertained to drug analysis alone, likely reflecting the routine use of evidential

Conclusion

Following new legislation for DUID in 2017, a continuously growing number of DUID cases have been investigated by blood analysis in the Netherlands. It can be concluded that drug-impaired driving is prevalent across all age groups, but particularly among younger male drivers.
Traditional DOA such as THC, amphetamine and cocaine are still highly prevalent in DUID cases, despite the rise in recent years of NPS.
Future research should include the scientific evaluation of the current legislated list

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgment

This article is dedicated to dr M. Verschraagen, who deceased on August 17th 2024. She contributed to both the implementation of the legislation mentioned in the study, as well as discussions on the presented study.

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