MISSOULA, Mont. -- Judges order some convicted of drunk driving to install ignition interlock devices, a machine that will not let you start your car if you are drunk. But we found one Missoula judge who doubts it is working.

Interlock devices are supposed to stop repeat offenders from drinking and driving.

That is why Judge John Odlin orders them for all people convicted of driving under the influence.

But, some people are not following the court order and having the devices put on their cars.

"I thought that it was happening, but apparently it is not," says Odlin.

On Wednesday, a multiple DUI offender was brought before Odlin on a charge of operating his vehicle without an interlock device, a misdemeanor. The case made Odlin question his strategy.

"Whether or not it is completely effective, I'm not positive," says Odlin.

The Department of Justice in Helena says they will not issue a probationary license to an offender, allowing him limited driving privileges, unless an interlock device is installed. But a justice spokesman says the legislature needs to look at DUI laws more closely, but admits there is little to be done to stop someone if they want to break the law.

Warrior Auto Works partners with the courts to install interlock devices. They say sometimes people do not show up for their appointments for financial reasons.

"They'll ride their bike, walk. One guy said that the state is not going to tell him how he can and can not drive," says Darrin Traver, owner of the shop.

Judge Odlin admits, there may not be a silver bullet to protect Montanan's from repeat drunk drivers, but he is willing to try anything.

"If we have some other way that we can do it, go for it, but I don't know what it is," says Odlin.