Mirror image rule - sustany/dvg GitHub Wiki

In contract law, the mirror image rule is a doctrine requiring any acceptance to be an unconditional assent to the terms of the offer. Thus, at least historically, any acceptance had to embrace the pricing and other information included in an offer, or there would be no binding contract.

In modern commercial settings, a binding contract is often recognized despite minor discrepancies between the offer and acceptance.  For instance, under the Uniform Commercial Code, a clearly expressed acceptance can create a binding sales contract even if the acceptance contains added or different terms when compared to the offer. See UCC § 2-206(3).