Police Officer Crosses ‘The Line’ with Traffic Stop for Improper Lane Usage

March 13, 2019

In a recent case, People v. Mueller, 2018 IL App. (2d) 170863 (2019), the Second District Appellate Court held that driving on a lane dividing line does not constitute the offense of improper lane usage under 625 ILCS 5/11-709(a). Police officers should pay particular attention to this holding because violations of Section 11-709(a) often serve as the basis for traffic stops to detect impaired drivers. Notably, the Court’s analysis in Mueller does not overrule existing cases that allow 11-709(a) to serve as a basis for a traffic stop when a motorist is weaving or driving erratically within their lane, even if they do not cross a lane line.

In Mueller, testimony of a McHenry County Sheriff’s Deputy at the hearing on the motorist’s motion to suppress provided the basis for the trial court’s ruling that a violation of Section 11-709(a) did not occur, and the Deputy’s seizure of the motorist was not valid. The Deputy testified that he observed the vehicle’s driver’s-side tires roll onto the yellow centerline for a few seconds without crossing the line. The vehicle returned to its lane, but the Deputy could not recall if the vehicle did so smoothly or abruptly. Further down the road, the passenger-side tires of the vehicle temporarily touched the fog line but never crossed the line. The vehicle moved back into its lane without any unusual actions. Lastly, the vehicle’s passengers side tires momentarily drove onto the fog line again but never crossed the line. The Deputy performed a traffic stop and conducted a DUI investigation resulting in the motorist being placed under arrest for DUI.

In granting the motorist’s motion to suppress, the trial court reasoned that simply driving on the centerline or the fog line did not create a reasonable suspicion that a motorist violated Section 11-709(a). In upholding the trial court’s ruling, the Second District Appellate Court analyzed what constitutes a “lane” for purposes of Section 11-709. While the Illinois Vehicle code does not define the word “lane,” the Court reasoned, relying in part on the Illinois Secretary of State’s rules of the road, that a line is considered part of the lane. A motorist does not commit a violation of Section 11-709(a) by merely driving on the lane line.

An important take-way from the opinion is the Court’s analysis of the State’s forfeited trial court argument that the motorist violated Section 11-709(a) by weaving or driving erratically within her lane. The Court’s holding leaves weaving or driving erratically within a single lane of traffic as a basis for a traffic stop under Section 11-709(a) untouched. As a result, before an officer performs a traffic stop of a vehicle for a violation of Section 11-709(a), the officer must observe the vehicle cross over a lane line paying attention to whether the lane deviation is caused by a roadway condition such as a pothole, debris, or a curve in the roadway. If the lane deviation is not due to one of these conditions, a violation of Section 11-709(a) has occurred and the officer can validly stop the vehicle. If a vehicle does not cross over a lane line, the vehicle’s movement within its lane must be erratic or constitute weaving in order to justify a traffic stop under Section 11-709(a). The officer performing the traffic stop must be able to clearly articulate the observations that served as the basis for the traffic stop both in their police report and during their testimony at any suppression hearing. The officer must be able to articulate the facts supporting the traffic stop and create a clear record for the appellate court if the trial court’s ruling on the motion to suppress is challenged by either side.