CHICAGO (CBS) — Illinois Attorney General Kwame Raoul and Special Prosecutor Joseph McMahon are asking the state’s highest court to order a new sentencing hearing for former Police Officer Jason Van Dyke, who was sentenced to less than seven years in prison for the murder of Chicago teen Laquan McDonald.

Raoul and McMahon filed a petition for a writ of mandamus, challenging the legality of that sentence. They argue it was improper for Judge Vincent Gaughan to sentence Van Dyke only for his conviction for second-degree murder and not for the 16 counts of aggravated battery, which they noted carry a longer minimum sentence.

“This is the first step in asking the court to declare that the trial court improperly sentenced Jason Van Dyke for the murder and aggravated battery of Laquan McDonald, and to order a new sentencing hearing,” Raoul said.

McMahon said he has spoken to McDonald’s family several times since the sentencing, and they support the decision to challenge Gaughan’s ruling.

“I have indicated a number of times that this whole process has taken an incredible toll on Laquan’s mother, Tia Hunter. I think she would like the process to be over. Whatever the outcome, she would like the process to be over,” he said. “I think, to the extent that she can move forward, I think the end of the process will help her move forward, understanding that a mother is never really able to move forward from the loss of a child.”

Last month, Gaughan sentenced Van Dyke to 81 months — or 6 3/4 years — in prison for second-degree murder, ruling that charge was a more serious crime than aggravated battery.

Raoul declined to say if he believed that sentence was too lenient, stressing he believes Gaughan did not follow the law.

Raoul and McMahon pointed to Supreme Court precedent that second-degree murder is a less serious offense, since aggravated battery has a more serious penalty. Judge Gaughan cited a dissenting opinion in that case in sentencing Van Dyke for the second-degree murder charge, rather than the aggravated battery charges.

“I’m not casting aspersions on the judge. The question is whether the sentence was consistent with the laws of the state of Illinois, and it is our belief that the sentence was not,” Raoul said.

McMahon said he was satisfied with the sentence Van Dyke received, but he wants to make sure the judge followed the law and court precedents.

“I think the bigger message in this case is to make sure that the sentence that is imposed is a sentence that is lawful under both the legislative intent and the law as set down by the Illinois Supreme Court,” he said.

Jennifer Blagg, an attorney working on Van Dyke’s appeal, called the petition challenging Van Dyke’s sentence a “purely political” decision.

“The law is clear, and the judge complied the law when he sentenced Mr. Van Dyke to second-degree murder. Let’s be clear, the filing today is purely political,” she said. “This case has always been about politics, and it continues to be about political decisions.”

Blagg said it was “ludicrous” to suggest that second-degree murder is a more serious crime than aggravated battery.

“There’s not a person watching this newscast today that would think that shooting someone was less serious than shooting and killing someone,” she said.

Raoul said it’s “nonsense” to suggest the decision to challenge Van Dyke’s sentence was a political one.

“This is a question of law and it’s in the interests of justice that the law be followed, no matter who the defendant, and no matter who the victim is in a particular case; and that is not a political question, that is a question of law,” Raoul said.

McMahon said he was notified last week that Van Dyke’s defense attorneys have filed a notice of appeal in the case, but he noted that does not give prosecutors an opportunity to challenge the sentence when they respond to Van Dyke’s appeal.

“This was kind of our one and only opportunity to challenge the legality of the sentence,” he said.

If the Illinois Supreme Court does order a new sentencing for Van Dyke, Raoul said he and McMahon will ask the court to also order the judge to sentence Van Dyke for all 16 counts of aggravated battery.

If Van Dyke’s current sentence stands, he likely would serve less than three years in prison, given credit for time served and good behavior. Van Dyke has been in custody since he was convicted last October.