Federation Security agent
The ID card of the agent
The officer that arrested Dr. McCoy in 2285 identified himself as Federation Security. The guards shown later around his holding cell wear with specialized uniforms that differed from those worn by Starfleet Security, but wear what looks like Starfleet insignia. (Star Trek III: The Search for Spock)
In his text commentary on the DVD, Michael Okuda refers to this organization as civilian security despite their insignia. If so, it marks the only appearance of a 23rd-24th century police force operating on Earth aside from Starfleet.