Michael Brelo found not guilty of involuntary manslaughter in connection with fatal shooting in 2012.
Baltimore's chief prosecutor faces a backlash after charging six police officers over the Freddie Gray's death.
Police Commissioner Anthony Batts announced on 30 April that their investigation was completed a day earlier than expected.
Baltimore is two cities: the crime-ridden area from The Wire, and a gleaming city on the waterfront.
The event, which is being organised by Mass Action Against Police Brutality on Facebook, is set to take place in front of the Boston Police Department Headquarters.
The lawsuit also names former Ferguson Police Chief Thomas Jackson and former Ferguson Police Officer Darren Wilson as defendants.
Reserve deputy faces manslaughter charge over shooting of African American Eric Harris
The officer who shot the 17-year-old has been placed on desk duty while the investigation is ongoing.
FBI to investigate 10 deputies who were filmed beating a suspect who lay on the ground.
Police call incident an 'ambush' by protesters as the two injured officers are out of hospital.
Victim suspected of mental illness as he was acting erratic when shooting took place.
In video uploaded to Facebook, five shots heard as victim is identified as 'Africa'.
Deaths of Michael Brown and Eric Garner remembered on MLK Day on Monday 19 January.
Possible civil rights violations in Dontre Hamilton's death to be probed.
Crowds of protesters took to the streets of New York and other US cities for a second night.
Protests erupt after a white police officer was cleared in the chokehold death of Eric Garner.
At what point are police officers around the world legally permitted to use force to control crowds?
Thousands of people rally in US cities against the Ferguson grand jury decision.