The DC Court of Appeals in Ken E. Smith v. U.S., on December 4, 2014, reversed a lower court drug conviction and denial of motion to suppress based on the tainted derivative evidence doctrine, which excludes all evidence — primary and secondary obtained and gathered in violation of the 4^th Amendment.

Specifically, Smith’s car was stopped due to having an obstructed license plate and subsequently marijuana and drug paraphernalia was found on him and in the car.   An arrest warrant was requested by the Officer and issued based on the affidavit submitted and approximately two weeks later Smith was located, arrested and additional drugs were recovered from him — the second time — justifying second set of charges.

At trial, Smith filed a motion to suppress all evidence seized from him arguing that the initial stop was unreasonable, illegal and thus the evidence collected subsequent to the stop, as well as the evidence seized in conjunction with the arrest warrant are both equally tainted and must be suppressed. Defendant Smith argued that the license plate cover frame, which obstructed “taxation without representations” portion of the license did not violate the DMV regulation which requires the identifying information of the license plate to be unobstructed. The trial court agreed and suppressed the first set of evidence seized however did not extend taint and exclusion to the second set of evidence obtained as was gathered through a valid arrest warrant.

The Court of Appeals disagreed and ruled accordingly:

We hold that where an officer‘s mistake of law leads to a warrant premised on tainted evidence, derivative evidence obtained pursuant to that warrant must be excluded, unless there is an independent source for the evidence or sufficient attenuation to ―purge the taint. The traffic stop at issue was premised on a ―mistake of law, namely, that a license plate frame partially covering the District of Columbia motto on a license plate violated a municipal traffic regulation when no such violation actually occurred… A mistake of law cannot provide the objective basis for reasonable suspicion or probable cause and therefore cannot support a valid warrant… Accordingly, because the record does not demonstrate that the officer would have come upon the derivative evidence at issue in the absence of the unlawful traffic stop and there was no independent source or other attenuation to purge the taint of the initial illegality, the exclusionary rule applies and the derivative evidence must be suppressed.

Essentially as the 4^th amendment protects persons from unreasonable search and seizure – if the stop is illegal, even if marginally illegal — it would be also inherently unreasonable and thus the fruit of such illegal stop must be suppressed.

The purpose of exclusionary rule (excluding evidence obtained in violation of the 4^th amendment rights) is to discourage and dissuade police from misconduct, and to ensure evidence is not tainted. Such rule not only applies to a primary source of evidence but also to the secondary or derivative evidence: here the evidence obtained from the execution of the arrest warrant.

However, the independent source doctrine will purge the tainted evidence. If there is “sufficiently attenuated or independent source” for obtaining the evidence, remote and removed from the initial illegal stop – then the secondary or derivative evidence would be admissible.

Here no such attenuation or independent source existed and the execution of the arrest warrant and seizure of the secondary-derivative evidence was directly linked and connected with the initial illegal stop, search and seizure and thus must be suppressed and dismissed.