Judge Barry G. Williams on Wednesday declared a mistrial in the trial of Officer William G. Porter on all four counts.
Porter, 26, was charged with involuntary manslaughter, second-degree assault, reckless endangerment and misconduct in office in the April arrest and death of Freddie Gray.
Attorneys will appear in court in front of an administrative judge Thursday to pick a retrial date. Porter is not expected to attend.
Gray, 25, suffered a broken neck and severe spinal cord injury in the back of a police transport van after his arrest on April 12. His death a week later prompted widespread protests against police brutality, and his funeral was followed by the most intense rioting and looting in the city since the assassination of Martin Luther King Jr. in 1968.
Baltimore State's Attorney Marilyn J. Mosby charged Porter and five other officers in Gray's arrest and death on May 1, and many have watched the proceedings in Porter's trial closely.