Janice Lester Doctor Janice Lester was a Human scientist of the Federation in the 23rd century . Early career . Lester ' s early career included a period of service in Starfleet . She spent a year alongside James T . Kirk and they became romantically involved . The lack of opportunities for a woman to command a starship struck both Lester and Kirk as unfair , but she became embittered by the career barrier . Their relationship soured to a point where Kirk felt she was punishing him for her circumstances . Years later , Kirk said " " we ' d have killed each other " " if they had stayed together . Lester recalled that Kirk walked out on her " " when it became serious " " . Lester abandoned her career in space , but continued to study every detail of a starship ' s operation . She nursed powerful resentments for the femininity that stood in her way , and for the masculinity that served Kirk so well . From 2267 to 2269 , Lester was the leader of an expedition to Camus II , exploring the ancient remnants of an advanced civilization . Among the ruins , she discovered a sophisticated mechanism still in working order . The device was capable of life - energy transfer – the exchange of one being ' s complete personality and memory with another ' s . Her plans to use the device herself required several month s of preparation . The expedition ' s incompetent physician , Dr . Arthur Coleman , bore an unrequited love for Lester . Together , they killed the expedition ' s entire staff by quietly exposing them to celebium radiation . The mysterious deaths announced by a distress call were meant to attract the attention of a starship , and the answered the call on stardate 5928 . 5 . Lester as Kirk . Kirk arrived at Lester ' s bedside , where she appeared to be near death . Not expecting danger , Kirk was easily ensnared . Lester activated the life - energy transfer device , and was immediately thrilled by her possession of Kirk ' s body . The transfer would eventually return the exchanged persona to its original body , as long as both remained alive . Drug ged and disoriented within Lester ' s body , Kirk was easy prey , but Lester ' s spontaneous gloating monologue prevented her from strangling Kirk before Dr . Leonard McCoy arrived . Lester eagerly boarded the " Enterprise " as the Captain , satisfied to finally have the command she felt was rightfully hers . Kirk was still a liability as long as he remained alive in sickbay , but the exclusive care of Dr . Coleman kept Kirk isolated from the crew . Lester ' s attempt to emulate a Captain ' s behavior was marginally successful at first , but her composure degraded at any hint of scrutiny from the officer s familiar with Kirk . Dr . McCoy soon challenged the Captain ' s mental health , and insisted on tests that ultimately proved negative for any illness . Spock discovered the truth of the situation through a brief mind meld with the imprisoned " Janice Lester " , but their attempted escape was halted by Security officer s ignorant of the Captain ' s strange new behavior . " Captain " Lester convened a court martial , charging Spock with mutiny . Whatever support Lester believed she had , it all but evaporated during her farcical prosecution and hysterical closing rant . Once Lester announced the impending execution of Spock , the " Enterprise " crew was on the verge of actual mutiny . Symptoms of the waning personality transfer forced Lester to make a final attempt to kill Kirk . The two touched in a brief struggle , and the misplaced personalities returned to their proper bodies . Broken , incoherent , and sobbing in her complete failure , Janice took her accomplice Coleman ' s arm and wanted him to kill Kirk . Coleman offered to help rehabilitate her with the assistance of McCoy , who escorted them both to sickbay . Kirk couldn ' t help but feel sorry for the poor , mentally unstable , twisted - minded woman , who was driven mad not only by her ambition of craving the power to command a starship , but also her hatred and jealousy of the captain she once loved , then wanted dead . Kirk felt her life could have been as rich as any woman ' s , " if only . . . " ( ) Appendices . Background Information . Janice Lester was played by actress Sandra Smith and William Shatner . The character was originally named Janice Lisette , however she was renamed to avoid confusion with writer Jean Lisette Aroeste . ( " " ) Lester ' s remark to Kirk , that his world of Starfleet captains did not admit women to their ranks , implies the Starfleet culture of the 2260s was more sexist than its 20th , 21st , 22nd or 24th century counterparts . An interpretation offered by the suggests Lester ' s comment referred to Kirk ' s inability to maintain a relationship , due to his responsibilities as a starship captain . It also states that Gene Roddenberry , on the other hand , admitted in his later years that the line was simply sexist . Assuming that such blatant sexism was indeed policy or practice in Starfleet , it seems that by the 2280s and the 2370s , the bias against women commanding starships had been corrected . In the early scenes of , a woman is shown to be in command of the . Also , throughout the series , Kathryn Janeway is shown to be in command of the . Additionally , Erika Hernandez was captain of " Columbia " NX - 02 a century before " Turnabout Intruder " and Philippa Georgiou was captain of the USS Shenzhou over a decade before Lester ' s remark . Some fans have attempted to reconcile this information by suggesting that Lester may simply have been insane and used sexism as an excuse for her own inability to command . Apocrypha . The " Focus on . . . Star Trek " comic " Captain ' s Personal Log " stated that she was taken to Starbase 2 , where she would await transport to Elba II . In the alternate timeline of the novel " A Less Perfect Union " , she served on the UESS " " as a security officer .