The link between the defendant's conduct and the prohibited result — proved in two stages, factual and legal, before liability for a result crime can attach.
A defendant who satisfies the 'but for' test may still escape liability, because the law demands more than a bare factual connection. This chapter begins with the two-stage structure of causation and the 'but for' test, then moves to legal causation and the requirement that the defendant's act be an operating and substantial cause without needing to be the sole one. It explains the thin skull rule, under which the defendant takes the victim as found, including characteristics beyond physical conditions. Finally, it works through intervening acts — when medical treatment, natural events, the victim's own conduct such as escape attempts or self-injection, and third-party responses will or will not break the chain.
