Chain of command in police departments?

Answer 1

Although there is wide cooperation (occasionally not) between US law enforcement agencies, there is no nationwide chain-of-command which exercises control over them. Every department is an agency of the executive branch of government of whatever jurisdiction they are formed under. Internally, most departments follow a more-or-less semi-military internal chain of command with a Chief at the top, and then (in descending order) Assistant Chiefs, Deputy Chiefs, Majors, Captains, Lieutenants, Sergeants, Corporals, Officers. Some department designate the differences in ranks using other terminology (Superintendents instead of Chiefs - Senior Officers or Privates First Class, etc.) but basically the majority of law enforcement agencies follow this model.

Answer 2

A system whereby authority passes down from the top through a series of executive positions, military ranks or police ranks in which each is accountable to but one direct superior.