R v Blaue (1975) 61 Cr App R 271 is an English criminal law appeal in which the Court of Appeal decided, being a court of binding precedent thus established, that the refusal of a Jehovah's Witness to accept a blood transfusion after being stabbed did not constitute an intervening act for the purposes of legal causation.

The defendant, Robert Konrad Blaue, entered the home of an 18-year-old woman, Jacolyn Woodhead, and asked for sex.

When she declined his advances, he stabbed her four times; one wound penetrated her lung which necessitated both a blood transfusion and surgery to save her life.

[2] The prosecution did not challenge unrelated evidence that the defendant was suffering from diminished responsibility which reduced murder to manslaughter, decreasing the starting point for any sentencing.

[2] The defence argued that the refusal to accept medical treatment broke the chain of causation (in modern comparative and ancient law in Latin this is called a novus actus interveniens) between the stabbing and her death.