Common Law: Traditional "Mirror Image" Rule. The traditional contract law rule is that an acceptance must be the mirror image of the offer.Several possible justifications are explored, and the resulting analysis is applied to various expression rules in the law of offer and acceptance. Acceptance is the agreement to an offer resulting in duties, obligations, or benefits for one or more of the parties. The offer requires valid acceptance for a binding contract to be formed. An offer can only make an agreement if it is accepted in its entirety. The main rule of validity for an acceptance is that it must be a clear and direct statement that all terms and responsibilities in the contract are accepted. Acceptance represents the meeting of the minds of the parties to the contract - both agree to exchange something for the other (payment, services, goods, etc.). Master the essentials of contracts from offer to legality. Ensure validity with these six elements for binding, enforceable agreements.