Coleman was removed from his last starship posting as chief medical officer after Starfleet Command, in cooperation with the Starfleet Surgeon General, cited him for "administrative incompetence" and making "flagrant medical blunders".
In 2267, Coleman joined an expedition headed by Dr. Janice Lester to Camus II as the expedition surgeon. For the next two years, he fell in love with and conspired with Dr. Lester to use an energy transfer device to switch her mind into the body of Kirk and to transfer his mind into her body. When the plot was foiled and Dr. Lester was deemed insane, he asked to be allowed to care for her. (TOS: "Turnabout Intruder")