DiLorenzo & Rush | Counselors of Law
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How do police know when someone is too high to drive?

On Behalf of | Aug 25, 2022 | Criminal Defense

Since New Jersey legalized cannabis for recreational use, police, lawmakers and courts have wrestled with the issue of determining whether someone is too high to drive. A recent report may pave the way for courts to rely on the testimony of people who have been trained to recognize drug intoxication.


When they pull over a driver on suspicion of drunk driving, police typically rely on a standard field sobriety test to determine whether the person appears intoxicated. In this test, police ask the driver to perform simple tasks like walking in a straight line and turning. Judging from how the driver performs the tasks, the police can get a good idea of whether the driver appears intoxicated. Police can also use a chemical breath test on the driver to determine their blood alcohol concentration. If the test shows a BAC of 0.08% or more, the driver is considered intoxicated.

Police do not have the same types of tools available when determining if someone is too intoxicated to drive safely. Police can observe a driver’s reaction times and other movements in a standard field sobriety test, but they have struggled to find a cannabis-oriented equivalent to the chemical breath test for determination of a driver’s BAC.

Police may use blood or urine tests when they suspect a driver is too intoxicated on drugs to safely drive. These tests purport to measure the amount of THC (the psychoactive element in cannabis) in a person’s blood, but THC can remain in a person’s system long after they have ceased to feel its effects. Many advocates say the tests therefore do not accurately measure whether a driver is safe behind the wheel.

Special master’s report

As part of an ongoing court case, New Jersey courts appointed a special master to assess the testimony of so-called drug recognition experts in determining whether a driver is too high to drive. In its recently released 332-page report, the special master’s office concluded that this type of testimony is reliable.

The term “drug recognition expert” refers to people who have undergone special training that is supposed to give them the ability to determine when someone is intoxicated by cannabis or other drugs.

It’s too early to say whether the report will lead to the widespread use of drug recognition expert training  in New Jersey, but it’s clear that the criminal justice system is serious about the issue of driving while high. People accused of this type of intoxicated driving will need to keep current on the fast-changing legal and scientific developments concerning the issue.