Narcotics Field Tests

Fundamentals of Procedural Law by Adam J. McKee

Narcotics field tests are tools used by law enforcement to identify suspected drugs quickly. These tests can lead to arrest and charges, even before laboratory confirmation. This section discusses important Supreme Court cases shaping the rules around these tests.

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Brinegar v. United States (1949)

The case Brinegar v. United States, 338 U.S. 160 (1949), raised significant questions about field tests. Brinegar was stopped and searched based on an officer’s belief that he transported illegal alcohol. The Supreme Court upheld the search and arrest based on probable cause, which can be influenced by a positive field test result (Brinegar, 1949).

United States v. Jacobsen (1984)

United States v. Jacobsen, 466 U.S. 109 (1984), dealt directly with field tests. After private FedEx employees discovered a suspicious substance, they informed the Drug Enforcement Administration (DEA), which performed a field test confirming it as cocaine.

The Supreme Court ruled the field test was not a “search” under the Fourth Amendment because it could only provide information about whether the substance was illegal. The test didn’t infringe on any legitimate expectation of privacy (Jacobsen, 1984).

Florida v. Harris (2013)

In Florida v. Harris, 568 U.S. 237 (2013), a drug-detection dog’s alert led to Harris’s arrest. The court held that a positive alert from a well-trained narcotics detection dog provided probable cause to search a vehicle. Though not a chemical field test, this case is relevant as the alert served a similar function in justifying a search (Harris, 2013).


The narcotics field tests, while effective for identifying potential illegal substances, bring up significant Fourth Amendment questions. As the Supreme Court has affirmed in cases such as Brinegar (1949), Jacobsen (1984), and Harris (2013), the results of these tests can often provide sufficient probable cause for a search or arrest, albeit with some constraints to protect individual privacy rights.

Modification History

File Created:  08/08/2018

Last Modified:  07/17/2023

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