Hartford - People charged with drunken driving in Connecticut could soon be required to install blood-alcohol testers in their vehicles, even if they've never been convicted.

A measure passed unanimously by the state's General Assembly requires first-time offenders to pay for the installation and monitoring of an ignition interlock device, a program that costs about $275 in fees plus monitoring expenses determined by the vendor. The bill is awaiting the signature of Gov. Dannel P. Malloy, who hasn't indicated whether he'll sign.

Mothers Against Drunk Driving said the legislation closes a gaping loophole in Connecticut's law by requiring thousands more offenders to use the devices, which the group contends are more effective at combating drunken driving than license suspensions.

"What we know is, if we get someone on the first offense, we start the process of taking the alcohol out of the car, separating driving and drinking," said Carol Ronis, communications manager for the national MADD organization, which began an effort in 2006 to encourage states to pass laws requiring ignition interlock devices for all offenders. The National Transportation Safety Board last year recommended states adopt measures to ensure their use is more widespread.

Currently, in Connecticut and 21 other states, there are laws on the books requiring ignition interlocks to measure a person's blood-alcohol content after a first conviction for driving under the influence. But that doesn't mean the person hasn't offended before.

Existing Connecticut law allows first-time offenders to attend an alcohol education program, along with a license suspension ranging from 90 days to a year. After the program is successfully completed, the driver's legal record can be wiped clean. A handful of other states have similar diversion programs for first-time offenders, which MADD is targeting.

Under Connecticut's bill, a license would be suspended for 45 days. But afterward, the offender would be required to have an ignition interlock device for a time period that can vary depending on the circumstances of the case. Out-of-state operators would be subject to the same penalties as in-state operators, except their driving privilege, as opposed to the license, would be subject to suspension. That privilege would not be restored unless the person installs and maintains an interlock device for the required period, according to DMV.

William "Skip" Church of Madison, a volunteer with Connecticut MADD whose son, Dustin, was killed by a drunken driver, said he'd prefer an immediate installation of the interlock device, citing statistics that nearly two-thirds of offenders still drive on a suspended license. But lawmakers have been hesitant to scrap license suspensions.

"Most of them view suspension as punishment - we've got to keep the punishment," Church said. "But if the punishment doesn't work and people are still driving drunk and people are getting killed, it really isn't punishment."

Church said there's a misperception that first-time DUI offenders made a simple mistake and will never drink and drive again. The Centers for Disease Control and Prevention, however, estimates a first-time offender has likely driven under the influence more than 80 times before being arrested.

Staff attorney David McGuire said the Connecticut chapter of the American Civil Liberties Union will monitor the situation but hasn't raised constitutional concerns about the bill because the group considers driving to be a privilege, not a right.

The Department of Motor Vehicles suspended the licenses of about 6,500 first-time offenders in 2013. If Malloy signs the bill into law, it would take effect in July 2015.

Sharon Geanuracos, DMV's legal director, predicts that many first-time offenders won't get the device installed and will instead allow their licenses to remain suspended. "There's a lot of people who just drop off the face of the earth and don't ever go back to the DMV to get their licenses restored," she said.