Officer Powell is shown on the videotape, which was taken by an amateur photographer, delivering most of the blows.
Officer Powell has agreed to waive his right to a conflict-free defense.
Prosecutors contend it was Officer Powell who delivered the blow.
Officer Powell insisted that was not what he meant.
In their first trial, the four officers were acquitted of all state charges except one against Officer Powell.
Officer Powell has denied delivering any blows to the head, even by accident.
On the videotape, he can clearly be seen putting a hand up to push back Officer Powell's baton.
"There is a significant threat to Officer Powell's due process anywhere," he said.
As a rookie on probation in training with Officer Powell, he was dismissed from the force, while the other men were suspended without pay.
Officer Powell was acquitted of all but one count.