The answer lies in four critical ingredients: an offer, acceptance, consideration, and mutual intent to establish a legal commitment. Under Illinois law, an acceptance occurs if the party assented to the essential terms contained in the offer (Klein v.Klein, 2017 IL App (1st) 153393-U, ¶ 23. Even in the case where one party signs a contract just before another (so. We do it with fair and reasonable contract terms that your clients can accept – and which protect you. A breach of contract occurs when the terms of that agreement are not followed. Before you can bring a breach of contract claim, a valid contract must exist.