accord and satisfaction american law institute anticipatory repudiation breach of contract commercial law common law consideration contra proferentem contract criminal law efficient breach exclusion clause firm offer frustration of purpose fundamental breach gift harvard law review high court of australia illegal agreement illusory promise impossibility impracticability integration clause invitation to treat liquidated damages mailbox rule mirror image rule misrepresentation multinational corporation negotiation new south wales non est factum novation offer and acceptance parol evidence rule penal damages privity of contract property law quantum meruit rescission shrink wrap contract small print specific performance statute of frauds supreme court of california third party beneficiary trusts and estates unclean hands unconscionability undue influence uniform commercial code