Q: At what point does speeding go from an infraction to a crime? 20 over? 30 over? Double the posted speed limit?

A: If you’re a fan of legal dramas, you may have heard about “prima facie” evidence as if it means they have a slam-dunk case.

State law on speeding is somewhat similar. “Exceeding speed limit evidence of reckless driving” states, “The unlawful operation of a vehicle in excess of the maximum lawful speeds shall be prima facie evidence of the operation of a motor vehicle in a reckless manner.” That makes it sound like speeding automatically makes you guilty of reckless driving, a serious criminal violation.

But legal experts would say that prima facie evidence doesn’t have to be conclusive or irrefutable. It should be understood as something that appears true when first examined but could be disproved.

For example, if you walk into the kitchen to find an empty Oreo cookies tray and see a dusting of chocolate crumbles on your spouse’s lips, you have prima facie evidence that they finished off the cookies. If your spouse says the dog ate the cookies, and then licked their face, and the dog has even more cookie crumbles on its mouth, well, now you have to weigh the veracity of the testimony.

And in a real court case (Schwendeman v. Wallenstein), evidence indicated that in addition to speeding, Schwendeman drove impaired, swerved to hit potholes and disregarded the pounding on the window and shouts from one of the four passengers in the bed of his pickup begging him to slow down. He crashed into a telephone pole, seriously injuring a passenger. The jury was instructed that speed alone was sufficient to convict Schwendeman of reckless driving. The U.S. Court of Appeals disagreed, saying that while there was plenty of other evidence to reach that conclusion, it couldn’t be reached from speeding alone.

Speeding is a high-risk behavior. It decreases time to react, increases stopping distances, and makes collisions more deadly. About one-third of traffic fatalities in Washington include speed as a factor. But speeding itself isn’t proof of reckless driving. While it often contributes to reckless driving, it’s possible that a driver could engage in high-risk behavior without reaching the threshold of recklessness. To meet that threshold a person must drive with willful or wanton disregard for the safety of people or property.

Recklessness requires intent. if you were driving 10 over the speed limit and, with no other contributing factors, were arrested for reckless driving your defense might be that you didn’t realize you were speeding because you hadn’t looked at your speedometer in a few miles. That doesn’t make it right, but without willful disregard, it doesn’t meet the definition of reckless driving.

Ultimately though, physics doesn’t care if you’re speeding because you’re reckless or you’re oblivious. Impact force is the same either way. So take it easy out there.

Doug Dahl writes a weekly column for this newspaper. He is with the state Traffic Safety Commission.