A lawyer for the wrong-way drunken driver who killed two people in a horrific Long Island crash — including a 7-year-old flower girl who was decapitated as she sat beside her mother — asked a Brooklyn appeals court yesterday to throw out his landmark conviction for depraved-indifference murder.

Jillian Harrington, lawyer for Martin Heidgen, told the appellate panel that depraved indifference requires proof that the defendant took criminal action while aware of the possible consequences. She said that could not be the case since he was drunk.

“At most, he was guilty of manslaughter,” Harrington said.

“He didn’t know he was going the wrong way and when he realized it, he started to slow down. He just didn’t know,” he was flying down the Meadowbrook Parkway going north in the southbound lanes, she said.

Prosecutor Maureen McCormick argued that no court has ever held that a defendant’s intoxication precludes a finding of depraved indifference.

Heidgen was convicted in the 2005 deaths of little Katie Flynn and limo driver Stanley Rabinowitz, 59, whose car Heidgen slammed into as they returned from a wedding. He was sentenced to 18 years to life.