Q: When you face a situation in two-lane traffic when you must enter the lane of oncoming traffic, is it necessary to signal that you’re moving back into the correct lane again? For example, when a police officer has someone pulled over, and they’re blocking the lane. I have been told signaling is not necessary.

A: This question proves it’s true that sometimes things are not what they seem (at least if it seems legal to you to not signal when changing lanes).

If you move into the oncoming lane to pass an ambulance at a roadside emergency, who are you signaling for as you return to your lane? Even so, if you think that signal isn’t required, you’re on the wrong side of the law. Sometimes we don’t know the law because it’s confusing.

Case in point: signaling in roundabouts. The last time I wrote about that, I got responses from multiple readers telling me that the law requires drivers to signal in a roundabout and explaining the exact process for doing so. The problem was that I got four different explanations for how to signal in a roundabout, and each one was in conflict with the other.

But sometimes we don’t know the law because, as Mark Twain is supposed to have said, “A falsehood travels around the world while the truth is still pulling on its pants.” Twain (or Winston Churchill or Thomas Jefferson or one of many other falsely attributed quotable folks) didn’t come up with that phrase; it’s been around for centuries. I can’t resist acknowledging the irony of a quote about truth being falsely attributed.

To counter those who told you signaling isn’t necessary, here’s the opening line of the law on turn signals (abridged for clarity): “No person shall turn a vehicle or move right or left upon a roadway … without giving an appropriate signal.”

In case you think there’s room for a little flexibility, the state Supreme Court has determined that there is not. In a ruling, the court concluded that even if there’s no one else on the road, and even if you’re in a dedicated turn lane, the law still requires you to use your turn signal.

Let’s say the law isn’t enough for you. Maybe you’re a maverick, and you need a reason beyond the state’s equivalent of your parents telling you, “Because I said so.” I have one. You perform how you practice. If you’re deciding whether to signal or not in low-stakes driving scenarios (like you described), you’re training your brain to make that decision in high-stakes situations too.

It’s a small cognitive load, but in a high-stress driving situation, you want to unload as many of those processes as you can to the automatic parts of your brain and leave the decision-making circuits free to quickly determine the right choice. We have a limited number of communication tools available when driving, and if you forget your turn signal in the stressful situation of trying to, say, merge right on a busy freeway to get to your exit, you might find yourself sharing the same coordinates with another car.

Automate that process so it always happens when you most need it. The law requires you to always signal when changing lanes, and it’s the right thing to do.

Doug Dahl writes “The Wise Drive” column weekly for this newspaper. He is with the state Traffic Safety Commission.