Oates took the helm of the Ann Arbor Police Department in Ann Arbor, Michigan, in the summer of 2001. Ann Arbor Mayor John Hieftje credited his newly hired police chief for mitigating attacks on Muslims after the 9/11 terrorist attacks. Oates oversaw the emergency and fire department in addition to the police department. Due to budget concerns, Oates reduced the size of Ann Arbor's fire and police departments by 20%. At the same time he helped reduce the violent crime rate by 24%. Hieftje also noted that his straightforward management style was an asset to the department.