The Iowa Supreme Court and the US Supreme Court saw it differently.
The Iowa Supreme Court ruled in March of 2014 that an anonymous tip does not give the police probable cause in order to initiate a DUI stop in State v. Koomia.
The case dates back to June 16, 2010, when Leon Koomia was stopped by officers for suspicion of drunk driving after dispatchers received an anonymous tip that Koomia and his friends had been drinking.
After the stop, Koomia failed the field sobriety tests and then registered a .088 BAC on the breath test. This was .008 over the legal limit. Koomia argued this was an illegal stop that violated his Fourth Amendment rights. The Iowa Supreme Court agreed and remanded he case for a new trial suppressing the field and breath tests.
About a month later, the US Supreme Court ruled that an anonymous tip was enough for a stop in Navarette v. California. In this case, the tip came from a woman that says she was ran off the road. The court found that the anonymous tip gave the officers reasonable suspicion of drunk driving.
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