Baltimore police officers facing trial over charges related to the 2015 death of Freddie Gray Jr. are not expected in court again until at least March, after the Maryland Court of Special Appeals scheduled a hearing that delays lower court proceedings. The delay is part of Officer William Porter’s effort to avoid testifying against fellow officers implicated in Gray’s death.

The appeals court announced Tuesday that a panel of judges will hear arguments in Porter’s case March 4, halting the Circuit Court trial of Officer Caesar Goodson Jr. and another officer. Originally due to go on trial this week, Goodson faces a charge of “depraved heart murder,” the most serious of offenses leveled at six officers involved in the April 12 arrest of Gray.

Gray, a 25-year-old African-American, sustained a severe spinal injury while riding in a van to a Baltimore police station. He died of his injuries a week later. The case prompted to days of civil unrest and rioting, along with peaceful protests, among Baltimore residents and social justice activists upset over the number of young black men dying at the hands of U.S. police.

Porter, who still faces trial on charges of involuntary manslaughter, second-degree assault, misconduct in office and reckless endangerment, is a material witness against Goodson and police Sgt. Alicia White. She faces the same charges as Porter.

Prosecutors told the Baltimore Sun that their cases against Goodson and White would be stymied without Porter’s testimony. After a judge declared a mistrial on his charges in December, Porter argued that forcing him to testify in his fellow officers’ trials would violate his Fifth Amendment right against self-incrimination. But Circuit Court Judge Barry Williams had ordered him to testify under limited immunity from future prosecution.

White's trial had been scheduled to begin Feb. 8, according to the Sun. Officers Garrett Miller, Brian Rice and Edward Nero, who are also charged in the Gray case, have trial dates scheduled for as soon as Feb. 22.