DUI/DWI: What is a Motion to Suppress?

by Jamison Koehler on September 22, 2009

If diversion is not an option for a client charged with DUI/DWI, the next step — also pre-trial — is to look at the legality of the stop. In other words, why did the police officer pull over the person to begin with? The Fourth Amendment of the U.S. Constitution prohibits unreasonable seizures. A car stop qualifies as such a seizure. In order to be reasonable, therefore, the police officer needs to have had reasonable suspicion or probable cause to believe that a traffic violation or some type of criminal infraction has occurred.

A Motion to Suppress is litigated before the case ever goes to trial. In a DUI/DWI case, it typically argues that:

(1) the police officer did not have reasonable suspicion or probable cause to stop the car;

(2) without reasonable suspicion or probable cause, the car stop was illegal; and

(3) any evidence collected as a result of this illegal stop should not be admissible against the defendant at trial.

This is the “tainted fruit” of the “poisonous tree” argument as spelled out in the famous U.S. Supreme Court case of Wong Sun v. United States.

Defense counsel might also base a Motion to Suppress on violations of other constitutional rights, such as the defendant’s right to counsel or due process. Say, for example, the police officer interrogated the defendant while he was in custody without reading the defendant his Miranda rights. Defense counsel could argue that any statements the defendant made in response to this interrogation should not be admissible against the defendant at trial. Or say that there was some mistake in the way the chemical tests were administered. Defense counsel could argue that the test results should be suppressed.

Ideally, defense counsel will be successful in getting all of the evidence “suppressed.” In this case, there will be no evidence with which the prosecution can proceed to trial and the prosecution will have no choice but to dismiss the case. In other situations, the court may rule that only some of the evidence will be suppressed. In this case, the prosecution might decide to proceed to trial with the evidence that remains.

Say, for example, that the police officer pulls the defendant over for driving at night without any lights. This is a violation of the motor vehicle code and, as such, serves as an adequate basis for a legal stop. When the police officers approach the car window, they immediately smell alcohol on the defendant’s breath and see an open beer container in the defendant’s hand. This provides them with reasonable grounds to investigate further. The defendant is unable to provide an proof of license, registration or insurance, his speech is slurred, and he staggers when the police remove him from the car. This is probable cause to arrest him for suspicion of DUI/DWI. Back at the station, in response to police questioning, the defendant admits that he drank a six-pack within two hours of his arrest. He submits to a breath test at the station, with the results coming back well over the legal limit, but the Intoxilyzer 5000 does not seem to be operating properly that day.

Given this scenario, defense counsel will probably be successful in getting both the defendant’s admission to how much he had drunk that day and the breath tests suppressed (that is, ruled inadmissible for trial). At the same time, the prosecution would probably still decide to proceed to trial. The evidence of the defendant’s operation of the car, the traffic violation, the odor of alcohol and the beer in his hand, and the defendant’s condition (slurred speech and staggering) could be enough to have the defendant convicted of driving under the influence (but not driving while intoxicated) without using the defendant’s statement or breath test results.

Coming next: litigating a motion to suppress on a DUI/DWI case.

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