Q: This time of year there are a lot of tractors driving on roads near farms. Is it legal to pass a tractor in a no-passing zone?

A: The Roman emperor Marcus Aurelius once said, “The impediment to action advances action. That which stands in the way becomes the way.” That quote has been popularized by modern stoic writer Ryan Holiday as “The obstacle is the way.” Being a fan of stoic philosophy, I’ve been asking myself, “If the obstacle is a tractor, and I’m in a no-passing zone, how does the tractor become the way?”

Any driver should know that solid center lines indicate a no-passing zone. The question then is, are there any exceptions?

Yes, there is one exception. The law doesn’t apply “when an obstruction exists making it necessary to drive to the left of the center of the highway.” (The driver still has to yield to oncoming traffic.)

That leads to more questions: What is an obstruction? And when is it necessary? Neither of those terms are defined in traffic law, but we can get a hint from Washington’s criminal code on how “necessary” might be understood. “Necessary” is defined, in part, as having no other reasonable alternative.

While “obstruction” isn’t defined, it is used in other places in traffic law, and most frequently it refers to a stationary object blocking the roadway. For example, the secure-your-load law describes objects that have fallen out of a vehicle and onto the roadway as obstructions.

We’re getting into interpretation of the law which, as is the job of the judicial branch of government. (I just rewatched that episode of Schoolhouse Rock and had forgotten that its describes the three branches of government as a three-ring circus with clowns.) I’ll share my understanding, but I’m no lawyer and my opinion carries no weight in a court of law.

A tractor fits the definition of a motor vehicle in the law, and it’s more appropriate to consider it a slow-moving vehicle than an obstruction. The law prohibits passing a slow-moving vehicle in a no-passing zone.

Even if you were to argue that a tractor driving on the roadway is an obstruction, I still don’t think you could legally pass it in a no-passing zone, because it doesn’t meet the “necessary” requirement. Since the tractor is driving, it’s going to eventually pull into a farm or reach a stretch of road where it’s safe to pass. You might not like the wait, but it’s a reasonable alternative to passing in a no-passing zone.

The exception to crossing the centerline in a no-passing zone is intended for inanimate objects, like a couch that’s fallen out the back of a pickup. It’s not going to get out of your way, so it’s necessary to go around it.

Maybe it’s not the tractor that’s the obstacle, but our sense of urgency. Then the tractor becomes the way; the way to practice patience.

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