You’ve heard, no doubt, that friends don’t let friends drive drunk. Well, here’s a twist: friends don’t let chronic problem drinkers and lousy drivers drive their cars.

That seems pretty obvious to most of us. But, apparently, it’s not obvious to all. That’s why the city of Portland has begun impounding vehicles driven by repeat offenders, whether they own them or not.

These people often can’t hold jobs and don’t have cars of their own. Yet, they somehow manage to slip behind the wheels of vehicles owned by family and friends.

Then the old habits take over. They drink, they speed and, sometimes, they kill.

One of the nation’s biggest traffic safety problems is not identifying and lifting the licenses of chronic offenders, but keeping them out of the driver’s seat.

Portland Police, according to a story in Tuesday’s Portland Press Herald, have begun enforcing a three-year-old ordinance allowing them to impound vehicles driven by repeat offenders.

State legislators have debated writing this same sort of power into state law. However, it’s run into one hitch: invariably, some innocent person ends up losing access to their car.

That may be a girlfriend, a spouse, a grandparent or a family friend. Chronic offenders don’t care if they are arrested, and they apparently don’t care much about these personal relationships.

About half the cars seized in Portland so far for being operated by chronic offenders belonged to a family member or friend. Portland police have been seizing them anyway, correctly reasoning that without a car to drive, these people won’t drive.

In Portland, the owner of the vehicle can appeal to the department’s hearing officer for return of the car, according to the Press Herald story. If the hearing officer is persuaded that the person has exercised due caution, then the vehicle is returned. If not, the vehicle stays locked up.

This builds some discretion into the law, and gives police time to help ensure the chronic offender doesn’t go right back home, grab the car keys and take off again.

Twice within the past year, drunk drivers who have killed people in our area and who have been prohibited from driving have been re-arrested for driving under the influence.

In one case, the offender had changed her name and obtained a car. In the other, the drinking driver had simply borrowed a car.

Giving police the power to impound cars operated by chronic offenders would send a signal to friends and family to do whatever it takes to keep the car keys out of their hands.

The Legislature should examine the results of the Portland experiment and reconsider this legislation for statewide use.