 A non-waiver clause is also valid and enforceable, but it is restrictively interpreted.An underlying principle of the law of contract ("pacta sunt servanda" or sanctity of contract) is that agreements seriously concluded should be enforced, but agreements that are clearly detrimental to the interests of the community as a whole, whether they are contrary to law or morality ("contra bonos mores"), or if they run counter to social or economic expedience, is not enforced.These contracts are illegal on the grounds of public policy.