Summary
The Iowa Supreme Court held that evidence obtained after a traffic stop based solely on a law enforcement officer’s mistake of law must be suppressed under the Fourth Amendment. The court affirmed suppression because an Estherville ordinance prohibiting U-turns was unenforceable in the relevant area absent required signage, and the parties stipulated that the officers made a mistake of law. A special concurrence agreed with the result but would have deferred choosing between competing mistake-of-law approaches.
Topics
Practice areas
Questions Presented
- Whether an officer's mistake of law can provide probable cause to justify a traffic stop under the Fourth Amendment.
- Whether evidence obtained as a result of the traffic stop must be suppressed when the officer accurately observed the conduct but mistakenly believed it violated an unenforceable traffic restriction.
Holdings
- An officer's mistake of law cannot provide the necessary probable cause to justify a traffic stop when the conduct observed did not violate an enforceable law.
- Evidence derived from the traffic stop must be suppressed because the State failed to establish probable cause for the stop.
Key quotations
“For the reasons described above, we conclude the district court properly granted Louwrens’s motion to suppress because the officers’ mistake of law cannot provide the necessary probable cause to justify the traffic stop at issue in this case.” (654)
“Courts applying the majority rule have concluded that the legal justification for a stop based on conduct accurately observed but mistakenly understood by officers to be illegal is not “objectively grounded.”” (653)
Factual background
Shortly before 1:00 a.m., Estherville police observed Donna Louwrens make a U-turn on Central Avenue and stopped her because they believed an Estherville ordinance prohibited the maneuver. The parties stipulated that Iowa Code section 321.237 required signs before the turning restriction became effective and that no signs were posted where Louwrens made the turn. During the stop, officers suspected intoxication, administered sobriety tests, and obtained breath-test results showing a blood-alcohol concentration above the legal limit.
Procedural history
Police stopped Louwrens's vehicle after observing a U-turn that they believed violated an Estherville ordinance. After the stop led to sobriety testing, breath testing, and an operating-while-intoxicated charge, Louwrens moved to suppress the resulting evidence. Based on stipulated facts, the district court granted suppression, and the Iowa Supreme Court granted the State's application for discretionary review and affirmed.