Most arrests for DUI start out as traffic stops for something else. Perhaps an officer sees that you have a light out or expired tags. Or, in the case of this story, perhaps the officer observes you cross the center line... once.

The Court of Appeals recently released an opinion discussing the intersection—pun intended—of two traffic laws. One regulates which side of the road a car should travel on. The other regulates in what circumstances a car can travel outside its lane.

The facts of the case are relatively straightforward. A woman was travelling down a state road, and a police officer was behind her. He observed her, over a straight two-mile section of road, weave within her lane consistently. The vehicle touched the centerline three times and crossed it once by a full tire length. At this point, the officer stopped the vehicle and arrested the driver for driving under the influence.

The driver was charged in Snohomish County District Court. Before trial, she moved to suppress all of the evidence from the stop, including her blood alcohol content results. She argued that her momentary crossing of the centerline did not violate state traffic laws and that the original stop was illegal. Relying on case law, the trial court agreed that there was no reasonable grounds to stop her and dismissed the case.

The State appealed, arguing that her driving violated another law, RCW 46.61.100, which requires vehicles to keep on the right half of the roadway. The case law relied on by the defendant and the trial court focused on RCW 46.61.140, which regulates when one can leave their traffic lane.

Although the court's discussion is not the most exciting, one aspect of it is informative. Under 140, vehicles can temporarily leave their lane without violating the law. The analysis under 100, however, is different.

Section 100 requires that a driver cross the center line with care. Inadvertent crossing of the centerline, as the defendant did here, violates section 100. Thus, the officer did have a basis for the traffic stop. The case was remanded for trial.

There are several important takeaways from this decision. First, know that it is these types of details that often make the difference between a DUI conviction and having a charge dismissed. The second lesson, however, may be more instructive to those on the roadways: If you are going to drift out of your lane, do it in a way that does not cross the center line.

Whether you were pulled over because you crossed the centerline or into the lane beside you, you need an experienced attorney if you are charged with a DUI. Attorney Steve Karimi has decades of experience both prosecuting and defending DUI charges in and around Seattle. If you are charged with a DUI, contact him immediately for a free consultation.