What the Blood Samples Revealed
Of all the samples that came back positive for narcotics, THC — the active compound in cannabis — was detected most frequently, appearing in 71 percent of cases. Amphetamines, including speed and ecstasy, came in second at 30 percent, followed by cocaine at 15 percent and GHB at 6.8 percent.



What makes the findings even more striking is the overlap between substances. One in five drivers who tested positive had not just one drug in their system but a combination of two, three, or even four. The most common pairings were THC with amphetamine or cocaine, and GHB with amphetamine — a concerning trend that points to a broader risk on the roads than single-substance use alone.



The profile of the typical drug-driving suspect is also telling. Nearly all — 92 percent — were male, with an average age of 29. Two out of every three drivers tested returned a positive result.

Younger drivers under 26 were more likely to have THC in their blood, while cocaine and amphetamine use became more common with age.

A Law That Changed Everything
The legal backdrop to this research matters. On July 1, 2017, an updated Road Traffic Act took effect in the Netherlands, introducing something the previous 1994 law had never included — defined threshold values for drug concentrations in the blood.

Before that change, the law simply prohibited driv.