HARTFORD, Conn. – An attorney for a Connecticut man who shot two adults and a 9-year-old girl to death on a Bridgeport street six years ago asked a state judge Thursday to cancel an upcoming penalty phase trial on whether he should be executed and to sentence him to life in prison without parole, citing the state’s repeal of the death penalty earlier this year.

A motion filed in Bridgeport Superior Court on Thursday in the case of Richard Roszkowski is the first formal legal challenge in a pending death penalty case against the repeal law, which applies only to murders committed on or after April 25 of this year.

Prosecutors and defense lawyers across the state had expected death row inmates and others facing possible death sentences to challenge their punishments because of the repeal.

The repeal law “represents the considered judgment of our legislature and governor that the death penalty is no longer consistent with standards of decency in Connecticut and does not serve any valid penological objective,” Roszkowski’s public defender, Michael Courtney, wrote in the 57-page motion.

“An execution carried out in the face of this judgment would plainly be cruel and unusual punishment and would violate the statutory prohibition against arbitrary death sentences and numerous constitutional prohibitions against arbitrary criminal laws,” Courtney wrote.

Courtney also said it appears that no state prisoner in U.S. history has been executed after that state abolished capital punishment.

“There is no history of such a practice because nothing could be more arbitrary and capricious than allowing eligibility for the death penalty to depend on the date of the crime,” Courtney wrote. “Under the statute, a capital felony committed on April 24, 2012 is death-eligible, but the exact same crime committed on April 25, 2012 is not.”

A hearing on the motion hasn’t been scheduled yet.

Connecticut this year became the 17th state to repeal capital punishment, and the fifth in five years. In the past five decades, the state has executed only one person, serial killer Michael Ross in 2005, who dropped his appeals and pushed for his death sentence to be carried out. Ten men are on the state’s death row.

Roszkowski, 47, a former Trumbull resident, was convicted of capital felony and murder in 2009 and sentenced that year to lethal injection for gunning down his ex-girlfriend, Holly Flannery, 39, her 9-year-old daughter, Kylie, and his former roommate, Thomas Gaudet, 38. Witnesses testified that Roszkowski stalked Flannery after she broke off their relationship and falsely believed Gaudet was having an affair with her.

But a judge later overturned the death sentence because of a mistake in the jury instructions and ordered a new penalty phase.

Jury selection was expected to begin in June, but was postponed. No new date has been set.

Last month, death row inmates tried to raise the repeal issue in their long-running lawsuit challenging the fairness of capital punishment in Connecticut, but a judge rejected the request.