Some states have have are making written driver’s license exams only available in English. This is clearly a method to deny licenses to illegal aliens. However, the advocates of this change often insist that this is a safety issue, and is unrelated to immigration. So let’s set aside the immigration issue and answer the basic question: must someone be fluent in English to be a safe driver?

The first thing we should do is look at the actual street signs you encounter over the course of a day. Some of them have no words at all and other signs have obvious visual clues. If you see an octagonal red sign, you don’t need to see the writing on the sign to know that this is a stop sign. Exclude street signs for a moment and count the number of different words you encounter. It’s a tiny subset of the English language.

Why are we excluding street signs? Because it’s not actually necessary to understand a street sign. You simply need to recognize the name. If I was in Paris looking for Rue Montorgueil, I wouldn’t need to understand what those words mean – I’d simply need to look for those words on a street sign.

Rue Montorgueil or Main street, it makes no difference. Comprehension is not required; only the ability to match a pattern.

So now we have this relative handful of important words. I could take someone who speak Spanish, French, or Italian and explain the concepts to them in their native language. After this lesson, they would know how to react to these signs.

So I would argue that the English fluency necessary to be a safe driver is relatively low. This shouldn’t come as a surprise to many people, as many of us probably know some functionally illiterate people who are able to drive without significant issues. Likewise, I’m sure that I could learn and understand Mexico’s traffic signs well enough to drive there, even though I know only a few words in Spanish.

Could I pass a Spanish language test on Mexico’s driving laws, though? Of course not. The level of fluency necessary to understand the test would be far higher than the level necessary to understand the signs. If I wanted to, I could create a test on your state’s driving laws that the vast majority of people would fail. I’d test simple concepts, but use words that very few people know.

The key takeaway here? A large vocabulary does not equal a better understanding of the laws.

There is actually a danger to denying licenses. If you look through the crime logs in your city, you’ll likely see a number of people cited for driving without a license. Lack of a license does not prevent many people from driving. However, it DOES prevent them from getting insurance – so they become uninsured drivers.