DUI probable cause: What's required?

Because we are an Iowa criminal defense law firm and therefore represent defendants charged with Operating While Intoxicated, or, OWI-- Iowa's drunk driving statute-- we commonly are asked the following question: what proof does an officer need to pull me over?

An officer must be prepared to present evidence of reasonable suspicion to believe a crime or the motorist possesses something illegal right in that moment. This is known as reasonable suspicion to believe a crime is afoot or contraband is present. Reasonable suspicion is "more than a scintilla" but less than probable cause.

If an officer otherwise has probable cause to believe that the motorist has committed a traffic, equipment, or some other law violation, that is also sufficient to conduct a traffic stop without a warrant. Probable cause is the subjective and objective belief, supported by training and experience, that the motorist is more than likely engaging in an illegal act. An easy shorthand for this is 51% percent proof the suspect is committing a traffic, equipment, or other law violation.

This can be aggravating to clients and potential clients who believe in their hearts that they could win a bench trial on the actual traffic violation-- the reason for the initial stop-- but that it will otherwise be upheld on the basis that the officer does not need absolute proof the violation occurred. That's because proof beyond a reasonable doubt-- think of it as 99% likely-- is far higher than the 51% proof required for probable cause.

In most cases, the officer who makes a traffic stop doesn't much care whether the motorist is cited for the traffic violation if he or she has escalated the stop to an OWI investigation.

That's because the OWI takes on the central role of the investigation and arrest.

Many clients believe the failure to cite for the underlying a traffic violation that served as the reason for the traffic stop is a smoking gun for an officer's lack of confidence in their reasoning. Typically, that's not the case and it is wishful thinking to assume that, unfortunately.

If you have been arrested for Operating While Intoxicated, or, OWI, Iowa's DUI law, contact us for a free initial