HARRISBURG - In the first overhaul of Pennsylvania's drunken-driving laws in a decade, the state Senate unanimously approved a measure Wednesday to require first-time offenders to use "interlock" devices before they can drive.

The legislation - approved 50-0 and expected to pass the House - stipulates that interlock devices must be installed for first-time DUI offenders with higher levels of alcohol.

The measure says anyone convicted of driving with an alcohol blood level of 0.10 percent or more must have their cars equipped with the devices that prevent operation when drivers have been drinking. That's slightly greater than the legal definition of intoxication of 0.08 percent.

"Reducing the number of drunk driving fatalities in Pennsylvania begins with strengthening the state's drunken driving laws," Jan Withers, national president of Mothers Against Drunk Driving, said in a statement issued immediately after the Senate action.

Under current law, repeat offenders who have had their licenses suspended for a year must get interlocks. There is no such requirement upon a first conviction.

Withers said the use of interlocks is more effective than license suspensions for stopping impaired drivers from killing people.

While only a handful of days remain in this session, Senate officials said they were confident that enough time remains for the House to approve the legislation to push the bill to the governor's desk.

State Sen. John C. Rafferty Jr., a Republican whose district includes parts of Chester and Montgomery Counties, said interlocks permit the convicted to keep driving as long as they don't drink.

"This would provide them with the opportunity to still get to work and provide for their families," he said before the vote.

If the measure becomes law, Pennsylvania would become the 32d state to make at least some first-time offenders use the device.

The Centers for Disease Control and Prevention says studies have shown that repeat drunk-driving decreases by about two-thirds when the devices are used.

Craig W. Stedman, the Lancaster County district attorney, called the vote extremely encouraging. "If this is signed into law, it will save lives," he said. "It is as simple as that."

Stedman, a leader on changing drunken-driving laws, said interlocks are a key tool Pennsylvania must expand to curb drunk driving.

He cited DUI statistics that showed New Mexico and Arizona saw alcohol-related driving deaths fall by about 40 percent when they expanded interlocks to first-time offenders.

Even with the current restrictions on their use in Pennsylvania, in 2013 interlocks blocked 50,000 attempts to drive by motorists who had been drinking, according to the Pennsylvania Department of Transportation.

In an article published last month, The Inquirer cast a spotlight on Philadelphia's lagging use of the interlocks in cars. The paper found that the city ranked last among the state's 67 counties for deployment of the devices.

dpurcell@phillynews.com

215-854-4915 @dylancpurcell

Inquirer staff writers Craig R. McCoy and Amy Worden contributed to this article.