REQUIRING INSURANCE companies to notify the state immediately when drivers dropped their coverage seemed like a good way to start cracking down on our state’s appallingly high number of insurance scofflaws. But we’ve tried lots of things in the past to make sure everybody pays their fair share, to no avail, so there was no way to know for sure.

Until now.

As The State’s Ben Werner reported recently, the percentage of uninsured drivers in crashes fell to 32 percent in 2005, down from 41 percent in 2003. That improvement is astounding. And there’s reason to believe we’ll see more of an improvement, since those statistics reflect just the first six months of the new law, which requires drivers to provide proof of new insurance within 20 days after they drop their old policy. If they don’t, police suspend their vehicle registrations and their driver’s licenses.

We can’t say for certain what caused this drop. It’s theoretically possible that uninsured drivers have suddenly become more careful drivers, but that’s unlikely; for one thing, it would contradict everything we know about the type of people who choose to break the law and foist their financial responsibilities off on others by driving uninsured (and usually untaxed, as well).

What we do know is that the decrease has come almost entirely since the start of the new program. What we also know is that the improvement hasn’t come because police are using that new power. Just the opposite: The number of people convicted for driving without insurance this year is down 7 percent, compared to 2003. And the number of vehicles with suspended tags has also dropped.

That means simply getting the letter from the state demanding action is resulting in precisely the action the state wants.

That’s consistent with what we know about human behavior: Most people obey the law merely because it’s the law. For those who need more incentive, that warning that tells them they’ve been caught is often enough to convince them to obey the law. Only a few actually need to be arrested and punished.

Of course, this new system isn’t perfect. It primarily identifies people who buy insurance in order to get their vehicle registered each year, then drop it until they have to provide proof of insurance again; so it won’t catch people who never bother to purchase insurance, or to register their vehicles and pay property taxes on them. But we hope that as more of the people who buy temporary insurance learn that they’re going to get caught, we’ll see a continued increase in the number of people who keep their insurance.

And we hope police will continue their on-the-road efforts to track down, and sanction, the rest of the insurance cheats. After all, those drivers aren’t just breaking some technical requirement of the law — they’re costing the rest of us money, in higher auto insurance premiums and higher property tax bills.