In the present experiment, utilizing the Film Fire' shooting simulation system, the effects of shift patterns and hardiness on police officers' judgments (decisions to (i) shoot at a suspect and (ii) taking cover during the confrontation) were examined. Sixty-one Authorised Firearms Officers were briefed on two “incidents” they would be asked to attend. The experiment took place at three different times, each time one hour before completion of the shift: at 1 p.m. (early day shift), 9 p.m. (late day shift), or 5 a.m. (night shift). In one incident the officer would be justified in shooting the suspect, whereas in the other incident it would be difficult for the officer to justify having shot the suspect. Because in both incidents the suspects were threatening the police officer, taking cover during both incidents would be desirable. Results revealed that most erroneous decisions occurred during the early shift, and that officers low in hardiness made more incorrect judgments than officers high in hardiness. Implications of the findings are discussed.