Those convicted of driving while under the influence a first time will join repeat offenders in having to pass a breath test before their car will start.

Gov. Dannel P. Malloy gathered with politicians and advocates in the shade of the Fairfield Police station’s front plaza Monday to sign a new law requiring ignition interlock devices for first-time DUI convictions.

Malloy said 40% of deadly traffic crashes involve alcohol, and that the law makes a number of changes for drivers convicted of DUI, the most important of which is requiring the devices in cars of first-time DUI offenders as well as repeat offenders, which he called “a big change.”

The new law goes into effect in July 2015.

Ignition interlock devices are cell-phone-sized devices wired into a vehicle’s ignition system that must be blown into before the car’s engine will start, according to a description in a press release from the governor’s office. The devices won’t activate a car’s engine if they detect a measurable amount of alcohol in the driver’s breath.

Malloy said research shows that the devices deter drinking and driving, and DUI offenders using them have acknowledged in surveys that the devices changed their behavior, even opting in some cases to keep them when no longer legally required. The new Connecticut law requires drivers to pay for the devices they are ordered to use, Malloy said.

Mothers against Drunk Drivers (MADD) board member Colleen Sheehy and her husband Skip Church, whose son died in a car accident with a drunk driver 10 years ago, appeared at the signing to thank the governor and legislators for passing the law. Sheehy said the driver who killed their son “should have had an IID in his car, and he did not.” MADD has advocated for the passage of such legislation across the country, and Connecticut is the 25th state to enact an ignition interlock law, according to Connecticut MADD Executive Director Janice Margolies, who also spoke at the ceremony.

The next step in technology to curb impaired driving, Malloy and Margolies said, is cameras in cars, which would ensure the devices are being used properly. Margolies predicted that within the next 10 years all new cars will come with them already installed.

Margolies said her organization is advocating for the elimination of suspension of drivers’ licenses “because we know the suspension of licenses doesn’t work.” The new law reduces the period of license suspension for some drivers convicted of DUI.

Malloy said the law was “one of several more stringent penalties and measures we are implementing to combat and reduce the kinds of behaviors that inevitably lead to crashes and deaths on our roads,” pointing to a law passed last year that increased fines and auto insurance rates for texting and phoning while driving.

Fairfield police have arrested 78 drunken drivers this year, Fairfield Chief of Police Gary MacNamara  told the crowd, working out to one DUI arrest every two-and-a-half days, he said.

State Rep. Tony Hwang (R-134), who attended the signing, said while legislation such as the IID law was important, a cultural change is necessary to reduce drunk driving deaths. Hwang said “having young people participate is the crux of that education,” praising a high school program in Trumbull that makes education about impaired driving part of the required curriculum.

Brenda Kupchick (R-132) was also present at the ceremony, and pointed out that the new law was important not just for its protection of the public from drunk drivers, but “to protect people with substance issues from themselves.”

The law passed the state General Assembly unanimously. State Sen. John McKinney (R-28) said after the signing ceremony that the bill’s bipartisan support showed “there are areas where we work together.”