The following premise could apply to just about any TREK series or movie, with the possible exception of the animated series. If you were a relative of a recently-deceased Enterprise crewman, and you wanted to sue the pants off Kirk (or Starfleet as a whole), which of the 60-odd fatalities of TOS would give your ambulance chasing lawyers the best case? In short, pick an individual victim from your preferred episode, and specific reasons why.
(For example, THE APPLE's Mallory's mom might sue Kirk for 70 billion credits on the grounds that Kirk never warned Mallory there were exploding rocks on the planet. Even Samuel T. Cogley would agree it's a clear case of negligence.)
What say you??