Under the so-called 'suicide by cop' theory, endorsed by the Ninth Circuit in the 2009 case of Boyd v. City and County of San Francisco, defendant cops are allowed to introduce evidence of a victim's alleged suicidal behavior in order to help the jury asses the credibility of an officer's version of a deadly force police shooting.
The idea is that the jury might find it more believable that the victim acted in a manner that justified shooting him or her if that victim had suicidal tendencies and thus wanted to die at the hands of the officer. The victim's version of events is of course left out of the picture because the victim is dead, and in any event just because someone may be "suicidal" at some point in time does not mean you go ahead and kill them.
The Ninth Circuit addressed 'suicide by cop' again in the recent Lal v. California opinion, which arose from the 2006 deadly force police shooting and killing of a despairing man by CHP officers. After a high speed chase prompted by a domestic disturbance, the victim threw rocks at officers, yelled 'just shoot me, just shoot me,' and used his cell phone to pantomime shooting a gun at the officers. The victim's family argued that the officers should have used better tactics to diffuse the situation, instead of killing him, but the trial court tossed the case and let the cops off hook on qualified immunity grounds.
"A police officer's immunity does not become less if his assailant is motivated to commit 'suicide by cop,'" the Court held. Implicit in the holding is that cops need not feel burdened by worries of lawsuits if they shoot to kill in alleged 'suicide by cop' scenarios.
The Court in Lal v. California made clear that in its opinion the officers were presented with requisite danger to justify deadly force with or without the 'suicide by cop' aspect, but the holding in Lal v. California would have been more helpful to mentally ill, agitated and despairing victims if it sent the message that cops should take more rather than less care when dealing with suspects who need help.