From Dictionary.com: frivolous (adj.) - self-indulgently carefree; unconcerned about or lacking any serious purpose. 

This lawsuit is EXACTLY frivolous by that definition. It is a shameless, self-indulgent money grab on the part of the plaintiffs, shaking down the city for actions EPD was forced into by their dead kinsman. They are clearly concerned neither about justice nor about the impact on their fellow citizens. 

Frivolous lawsuits are ones that aren't reasonable, and this is a textbook example. Anyone who has read my posts knows I am not exactly a fan of EPD, but it is not reasonable to argue that an officer with a rifle pointed at him was unjustified in firing his own weapon.