Maryland's highest court has released an opinion explaining its recent decision to force an officer charged in the death of Freddie Gray to testify against his colleagues.

The Maryland Court of Appeals issued its opinion Friday. Chief Judge Mary Ellen Barbara writes that compelling Officer William Porter to testify while he awaits retrial is not a violation of his Fifth Amendment right not to incriminate himself. The judge says there are ways to ensure that the testimony, which is protected by immunity, doesn't make it into his retrial. Porter's trial ended in a hung jury in December.

Gray died April 19, 2015, a week after his neck was broken in a police van. Six officers were charged in his death. One of them, Officer Edward Nero, is currently on trial.