There are two types of causation: factual and legal. Both needed to convict someone.
'But for' test
Pagett (1983) - where the defendant used his girlfriend as a shield in a shooting. As a consequence she died, however she wouldn't have died 'but for' him using her as a shield.
White (1910) - where the defendant intended to kill his mother but she died before from a heart attack. The defendant didn't cause her death so he was not guilty of murder.
The defendant can only be guilty if the consequence would not have happened 'but for' the defendant's conduct.
Cause in law
The defendant can be guilty even if his conduct was not the only cause of the consequence.
'De Minimus' rule - the defendant's conduct must be more than a minimal cause but it need not be substantial.
'Thin skull' rule - the defendant must take the victim as 'he finds him'. If a victim has something unusual about his physical or mental state which makes the injury more serious, then the defendant is liable for that more serious injury.
Blaue (1975) - where a young women was stabbed and died because she refused a blood transfusion as her religion does not allow it. The defendant was liable for her death as he had to take her as he…