Skip navigation
The Habeas Citebook Ineffective Counsel - Header
× You have 2 more free articles available this month. Subscribe today.

Drug Detection Using Fingerprints in the Works

by Matt Clarke

According to, scientists at the University of Surrey in the United Kingdom have developed a new forensic technique that, in as little as 30 seconds, analyzes sweat found along the ridges of fingerprints to determine whether a person has used cocaine within the previous 24 hours.

A research paper, recently published in Clinical Chemistry, said the assay detected traces of cocaine even after the subjects washed their hands with soap and water.

The researchers used 160 fingerprint samples collected from 16 people who admitted using cocaine within the past 24 hours when checking into a drug treatment program. The presence of cocaine was verified by testing saliva.

Additionally, there were 80 fingerprint samples (presumably from eight people) of nonusers. The report claimed the test correctly identified 99 percent of the users and gave false positives for only 2.5 percent of the nonusers.

Presumably, what the scientists are saying is that only one or two user fingerprints out of 160 samples showed up as nonuser and only two out of 80 nonuser fingerprints showed up as user.

Although that is an impressive achievement, it still could misidentify up to 25 percent of nonusers as users, if test results are based upon a single fingerprint showing use.

Regardless of its current or future accuracy, the fingerprint drug test may soon set established Fourth and Fifth Amendment case law on its head.

Police in many states already routinely demand fingerprint scans during traffic stops. The courts have generally upheld this practice, holding people have no Fourth or Fifth Amendment rights regarding the “non-invasive” use of a “non-testimonial” mark for identification.

This makes it a little different from using a person’s height, weight, or hair color for identification.

Less clear is the use of body fluids and expiration to collect evidence of a crime. A blood draws require search warrants—they are clearly invasive.

The breath test is less invasive, and the law surrounding it less clear. Search warrant requirements depend on the circumstances surrounding the breath test.

The problem is that police may well start requiring fingerprint drug analysis for every person they stop. A positive result would be used to justify search of a vehicle. That would be an entirely different purpose from the one considered by the courts in approving the right of police to take fingerprints to determine a person’s identify. Thus, the courts may have to take another look at whether demanding a person’s fingerprints is constitutionally permissible in that context. 


As a digital subscriber to Criminal Legal News, you can access full text and downloads for this and other premium content.

Subscribe today

Already a subscriber? Login



CLN Subscribe Now Ad 450x600
PLN Subscribe Now Ad 450x450
The Habeas Citebook Ineffective Counsel Side