It is unjust to punish a defendant for doing something that a reasonable person would have done in the same circumstances;

and

The law should encourage a defendant to choose the lesser and avoid the greater evil on grounds of public policy.

S murdered his mother and tried to claim his inheritance. There is a rule that no one should profit from his or her wrong, this overruled a clear statutory right of a son to inherit on intestacy. Hence statutes may be modified on grounds of public policy, as one was in this case (the principle was an existing common law principle that would have applied had she had died having made a will). Although this is a clear breach of the rule that clear and unambiguous words cannot be ignored, it surely accorded with Parliament's wishes.

Held: Using the 1966 Practice Statement to depart from the decision in Lynch.

Duress is not available as a defence to murder either to a principal or accessory. Morals, law and policy should deny a man the right to take an innocent life even at the price of his own.

Lord Hailsham;

"…the overriding objects of the criminal law must be to protect innocent lives and to set a standard of conduct which ordinary men and women are expected to observe if they are to avoid criminal responsibility…"

Held: Lord Denning MR;

If hunger were allowed as an excuse for stealing, or homelessness as a defence to trespass, it would open a door through which all kinds of lawlessness and disorder would pass; each would say his need was greater than the next man's.

Public policy reasons prevented someone who had had a bigamous marriage (and was hence void), claiming money that they were clearly statutorily entitled to.