DETROIT (AP) — The Michigan Supreme Court on Tuesday postponed the January trial for the parents of the teenager who killed four students at his high school, a victory for defense lawyers who argue that involuntary manslaughter charges don't fit.

The court ordered the state appeals court to hear an appeal from James and Jennifer Crumbley.

The order coincidentally emerged a day before the one-year anniversary of the shooting at Oxford High School, roughly 30 miles (50 kilometers) north of Detroit. Ethan Crumbley, who was 15 at the time, killed four students and injured six more plus a teacher.

He recently pleaded guilty to murder and terrorism and said James Crumbley bought the gun with the boy's money just a few days earlier.

The 16-year-old's parents are accused of ignoring his mental health needs and making the gun accessible at home. Defense lawyers argue that the Crumbleys can't be held criminally responsible for Ethan Crumbley's independent acts.

The Supreme Court said the appeal is limited to whether there was “sufficient evidence of causation” to send the Crumbleys to trial.

Justice Richard Bernstein was the lone dissenter, saying that issue could be addressed after a trial. Jury selection in Oakland County court had been scheduled for Jan. 17.

“The Crumbleys did not counsel EC in the commission of the school shooting or act jointly with EC in any way,” attorney Shannon Smith said in a court filing, using Ethan Crumbley's initials. “To the contrary, the Crumbleys had no knowledge that their son intended to commit multiple homicides.”

Defense lawyers and prosecutors, noting a gag order in the case, declined to comment on the Supreme Court order.