BOISE, Idaho (AP) - U.S. Sen. Michael Crapo will likely be required to install an ignition interlock device in his car to test his breath for alcohol as a result of his drunken driving arrest in Virginia. But that wouldn't have been the case in his home state of Idaho, which doesn't require the devices for first-time offenders.

The Spokesman-Review reports that 17 states, including Washington and Virginia, require the in-car breath tests to prevent even first-time convicted drunken drivers from starting their cars while under the influence. Idaho requires the devices for repeat offenders, however.

Crapo was arrested on suspicion of drunken driving last week and police have said the Idaho Republican registered a blood-alcohol level of 0.11 percent when he was pulled over in Alexandria, Va., after running a red light.

Crapo, a first-time offender who was known as a teetotaler due to his Mormon faith, has said he doesn't plan to contest the charges. His court date is Friday. Virginia law likely will require him to get an interlock device to drive, which prevents a vehicle from starting if the driver's breath reveals the presence of alcohol.

Related:

NTSB: Use ignition locks for all drunken drivers

Every state should require convicted drunken drivers, including first-time offenders, to use devices that prevent them from starting a car's engine if their breath tests positive for alcohol, the National Transportation Safety Board said Tuesday.

A growing number of groups are saying that Idaho also should require the ignition interlock devices for first-time drunken driving offenders. Last month, the National Transportation Safety Board sent a letter calling for states to require the devices for a first offense. Idaho Transportation Department spokesman Reed Hollinshead said the letter is under review.

AAA of Idaho and Mothers Against Drunk Driving of Idaho are also asking for tougher ignition interlock laws.

"When we looked at the data based on everything that's out there, this looks to be the strongest mechanism out there right now that would sort of trump everything we've done previously," said Dave Carlson, spokesman for AAA Idaho. He noted that while nationally about a third of highway fatalities are alcohol-related, Idaho's figure is higher at nearly 40 percent.

A study by the Insurance Institute for Highway Safety found that repeat offenses by first-time drunken drivers in Washington fell by 12 percent after that state expanded its ignition interlock law. Kansas, which passed an all-offender interlock law in 2011, found that in that first year the number of alcohol-related traffic fatalities dropped by half.

How does an ignition interlock device work?

Once the device is installed in the vehicle, it is then hard wired to the engine's ignition system. When the driver is ready to drive the vehicle, he or she will have to blow approximately 1.5 liters of air into a handheld alcohol sensor unit. If his or her breath alcohol content is over a preset limit, the device will not allow the car to start. -IgnitionInterlockDevice.org

Idaho's alcohol-related traffic fatalities fell significantly from 2007 to 2011, from 101 to 66, according to ITD data. But so did all traffic fatalities in the state, part of a long-term trend that experts attribute to everything from better-engineered cars and roadways to increased seat belt use.

During the same time period, the percentage of Idaho fatalities that were alcohol-related dropped from 43.5 percent to 39.5 percent but remained well above the national rate, which has been between 30 and 32 percent since 1995.

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