SALT LAKE CITY -- The lack of any law defining what a lane of traffic in Utah is, became the centerpiece of defense arguments on Wednesday for a former Utah Senate majority leader seeking to suppress evidence from a traffic stop in which he was arrested for suspicion of driving under the influence.

Defense attorney Ed Brass argued in Salt Lake County Justice Court that Sheldon Killpack never should have been pulled over and that all evidence from the stop -- including dash cam video of Killpack performing poorly during sobriety tests -- should be inadmissible. Judge Shauna Graves-Robertson did not specify when she would rule. Another hearing was scheduled for Sept. 7.

Brass contends video evidence doesn't support the erratic driving pattern described in the arresting officer's written report. During questioning, Utah Highway Patrol Trooper Raymond Thomson acknowledged the video didn't capture everything he saw the night Killpack was pulled over.

However, Thomson was able to identify several instances in the video where he said Killpack straddled or crossed over onto the broken line separating lanes of traffic. Prosecutors contend that gave Thomson reasonable suspicion to make the stop. Brass challenged Thomson's definition of straddle, saying not once did Killpack's vehicle appear on both sides of the line.

Thomson later clarified that, to him, straddling means hitting the broken painted line in the center of the road several times.

Even so, Brass argued that whether Killpack touched the line or not is irrelevant because nowhere in state or county law is the definition of a lane of traffic defined.

He says that makes it impossible for anybody to know where a lane begins and ends.

Killpack has pleaded not guilty to misdemeanor charges of DUI and failure to signal. Prosecutors allege Killpack's blood alcohol level was .11, above the legal limit of .08.

He resigned from the Legislature the day after his 2009 arrest.