“While particularly proficient in the area of tactical operations, the department lacks the training, leadership and culture necessary to truly engender community policing and to build and sustain trusting relationships with the community,” the report said.

There are 90 municipalities in the county, many of them with their own police departments. But the county’s department, with 855 officers, provides at least some services to 66 municipalities, as well as to the unincorporated areas in the county, according to the report. The actions of the smaller forces can have a negative impact on the county department, the report said.

The assessment was done by the Police Foundation, a nonprofit based in Washington, for the Justice Department’s Office of Community Oriented Policing Services. Officials reviewed departmental documents including training manuals and policies. They interviewed more than 200 people, including members of the force and residents. And they directly observed departmental operations, including preparations for the grand jury announcement in November in the death of Mr. Brown.

The police response to the grand jury announcement and other protests was hampered by inconsistent direction from leaders, deficiencies in communication within and between agencies, and the integration of assistance from other municipal forces “each with disparate missions, policies, training, equipment, and policing cultures,” the report said.

In preparation for the grand jury announcement, the county police consulted with community members, including a group called Lost Voices, among the most brash and vocal critics of police practices. Tactical and protective gear were kept out of public view until they were needed, and officials required a higher level of approval before deploying tear gas. Officers were given pocket-size cards with the First, Fourth and 14th Amendments, as well as copies of their sworn oath, the report said.