If you’ve been convicted of driving with a high blood-alcohol concentration, you may be in for a surprise the next time you try to drive.

Your car may not start.

If Maryland Senator John A. Giannetti Jr., D-Prince George’s and Anne Arundel, has his way, you would have a device installed in your car for a year that monitors the amount of alcohol on your breath. And each time you get in the car, you have to pass the test or you aren’t going anywhere.

The bill would require anyone found guilty of driving with a blood alcohol concentration of 0.15 or higher, shown by taking a breath test, to drive with what is called an ignition interlock system in their car for the next year.

The device is already in use in Maryland, installed in the cars of some 6,000 motorists, according to testimony Wednesday before a legislative committee. Judges now have the discretion to order installation of the device as a condition of probation, and people can volunteer to have them installed.

But Giannetti’s bill would make the device mandatory for those convicted of having blood alcohol concentrations above 0.15.

“People with interlocks do not re-offend,” Giannetti said. “The roads are safe with interlock on your car.”

The ignition interlock system connects to the car’s engine. Before the car can start, a driver must blow into a device to demonstrate that he or she has an alcohol level of less than 0.03. That would allow a beer or glass of wine for most people.

Even after drivers get underway, the device randomly requires breath tests while they are driving. If an alcohol level of 0.03 or higher is detected, the car’s horn honks and lights flash until the car is pulled over and turned off, or until the driver can pass the test.

During testimony before the Senate Judicial Proceedings Committee, Regina Averella, manager of public and government affairs for AAA Mid-Atlantic, said 19 states have already made ignition interlocks mandatory.

She also said “super drunk drivers,” those with a high blood-alcohol concentration, do the most damage on roadways as they’re more likely to crash.

Committee member Jennie M. Forehand, D-Montgomery, pointed out that the cord that attaches the ignition interlock to the car is long enough to reach someone in the back seat. She asked how the system would be able to know the driver is the one blowing into the device.

Jack Dalton, director of market development for National Interlock Service, explained that the company is looking into that problem and a new version of the device that could identify the person taking the test would be out in the next year.

“Our company is now working on something called positive ID,” he said, with National Interlock Service being one of the four companies providing interlocking systems in Maryland. “Our company takes a digital picture of the person taking the test.”

Dalton said that other companies will use identifiers like thumbprints, iris prints and voice prints to determine who is taking the test.

The Maryland Judicial Conference, which consists of the state’s judges, did not appear at th