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Roadside drug test kits are plagued by reliability issues

On Behalf of | Jun 1, 2023 | Blog, Drug Crimes |

Portable drug test kits are used by police and corrections departments in Colorado and other states to check suspicious substances during traffic stops and to screen inmate mail. These kits are popular because they only cost about $2 each and are very easy to use, but they are highly unreliable. They contain plastic bags filled with chemicals that change color when they are exposed to illegal drugs. The problem is that dozens of benign substances also make the chemicals change color. This is why a judge in California has ruled that the kits do not meet the admissibility standard for forensic evidence.


When individuals are arrested because portable drug test kits identified a suspicious substances as illegal drugs, they often agree to enter into plea agreements in return for more lenient treatment. This sometimes happens before suspicious substances have been sent to forensic laboratories for more rigorous testing. As a result, people are sometimes sent to jail or ordered to pay stiff fines for possessing legal substances. The National Registry of Exonerations maintains a database of cases involving people who were wrongly convicted of drug crimes. It reveals that at least 131 people have been convicted of narcotics possession or distribution in the last 10 years because drug testing kits identified legal substances as controlled drugs.

Benign substances

Portable drug test kits are inherently unreliable because so many benign and quite legal substances trigger the same chemical reactions as illegal drugs. The chemical that turns green when exposed to heroin also changes color when chocolate is tested, and the cobalt thiocyanate used to determine whether or not a suspicious substance is crack cocaine turns blue when exposed to more than 80 compounds including many acne medications and household cleaners. This is why a judge in Massachusetts said using the kits to screen for illegal drugs amounted to little more than “arbitrary and unlawful guesswork.”

Unreliable evidence

If you are arrested because a roadside drug test identified a substance as an illegal drug, you should demand a more reliable test. Prosecutors understand that portable drug test kits are unreliable, and they will usually agree to more rigorous testing when they realize that suspects also know this.

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