This paper offers two related things. First, a theory of singular causal statements attributing causal responsibility for a particular harm to a particular agent based on the conjunction of a positive condition (necessitation) and a negative condition (avoidability) which captures the notions of sufficiency and necessity in intuitive ideas about agent causation better than traditional conditio sine qua non based theories. Second, a theory of representation of causal issues in the law. The conceptual framework is that of Game Trees and (...) Games in Extensive Form. Causal conditions are defined set-theoretically over Game Trees; causal issues and fundamental distinctions (dependent versus independent intervening causes, foreseeability or not of harm etc.) arising in legal cases are accommodated by the device of a probability distribution over the game-tree representation of cases. (shrink)