A new state law that targets repeat felony drunken drivers will go into effect Friday. A prosecutor said it will apply only to a few drivers, but those it does affect are “potentially very dangerous.”

Under current law, if someone has a felony conviction for operating under the influence that is at least 10 years old, authorities cannot use that conviction against the person when considering whether a new offense should be a felony or misdemeanor.

The new law, effective Aug. 1, allows all prior felony OUI convictions to be applied.

An OUI becomes a felony if it’s a third OUI offense or if it results in a serious injury or fatal motor vehicle crash.

The bill that takes effect this week is a weakened version of another bill that originally sought to allow all OUI convictions, including misdemeanors, to be considered in determining whether a new offense should be a felony, but many lawmakers felt that would be too punitive, so the bill was amended to focus just on prior felony convictions.

Gov. Paul LePage vetoed the amended bill, saying it didn’t go far enough. His veto was overridden.

Walter McKee, an Augusta attorney and chairman of the legislative committee for the Maine Association of Criminal Defense Lawyers, said there has been some confusion about what the new law actually does.

“There has always been a lifetime look-back (for prior OUIs),” he said. “The difference now is, if you had a felony at any point, any new conviction is automatically a felony. But there is no way a court would not consider someone’s entire criminal history in looking at sentencing and conditions.”

Meaghan Maloney, district attorney for Kennebec and Somerset counties, said the new law may not be perfect, but it’s a step toward protecting the public from the worst offenders.

“Very few people will fall into this category, but those that do, we want to target because they are potentially very dangerous,” she said.

Rep. Tim Marks, D-Pittston, a retired Maine State Police trooper, introduced the bill in part because of people like David Labonte of Biddeford, who was accused of driving drunk in August 2013 when he allegedly struck a family riding bicycles and killed 52-year-old Jamerico Elliot. It was the fifth time he had been charged with OUI.

Labonte had OUI convictions in 1983 and 1988. However, when he was pulled over again for drunken driving in 2005, his prior convictions could not be used to upgrade the new charges to a felony because the first two OUIs were more than 10 years old. Because of the limit, his punishment consisted of a three-month license suspension and a fine of $600.

An analysis last year by the Maine Sunday Telegram found that 720 people were convicted of drunken driving three or more times between 2003 and 2013.

If the new law had been in effect, Labonte’s prior OUI convictions would not have come into play because those convictions were only misdemeanors, not felonies. But his license suspension would have been affected. License suspensions are the jurisdiction of the Secretary of State’s Office, not the courts.

When someone is convicted of OUI, the criminal penalty usually involves a fine and jail time. There is also an administrative penalty, usually the loss of a driver’s license. That penalty occurs before conviction.

The new law, in addition to including older felonies, also increases a license suspension from 90 days to 150 days for a first-time offense. A second offense within a 10-year period results in a three-year suspension. That change is likely to affect more people, and brings Maine closer in line with the license suspension periods imposed in other states.

Secretary of State Matthew Dunlap said the new law will target a select few repeat offenders. Of the nearly 4,000 people who were convicted of drunken driving in Maine last year, only 131 were felony convictions.

The number of OUI convictions statewide has also been dropping steadily over the past several years, Dunlap said.

“But all it takes is one awful case to remind people,” he said.