In Badie v. Bank of America (1998) 67 Cal.App.4th 779, the plaintiffs held credit cards issued by the defendant bank. When the plaintiffs first obtained their cards, the governing agreement did not contain an arbitration clause. It did, however, contain a provision stating that "all terms" of the card agreement were "subject to change" upon notice from the bank. After the plaintiffs obtained their cards, the bank mailed them a notice with their monthly bills stating the card agreement had been modified to require arbitration of any disputes. (Id. at pp. 785-786.) The plaintiffs contended the arbitration provision was unenforceable because they had not agreed to it, while the bank contended the plaintiffs' consent to the arbitration clause was unnecessary because they had already agreed to allow the bank to modify the terms of the card agreement, thereby effectively consenting to any subsequent changes made by the bank. The court noted the fundamental issue was whether the parties had agreed to arbitrate, since agreement is a prerequisite to a valid arbitration provision. (Badie, supra, 67 Cal.App.4th at pp. 787-788.) Evaluating the bank's argument the plaintiffs were deemed to have agreed because the bank had contractual authority to modify the terms of the agreement, the court noted "[t]he contract modification cases cited by the Bank . . . do not support the proposition that a party with the unilateral right to modify a contract has carte blanche to make any kind of change whatsoever as long as a specified procedure is followed. In fact, those cases suggest that a modification made 'in accordance with the terms of the contract' means, at least in part, a modification whose general subject matter was anticipated when the contract was entered into." (Id. at p. 791.) Based on these decisions, the court concluded there are three distinct constraints on the scope of amendments permitted under a clause authorizing the unilateral amendment of an agreement. The first, as with any contract, is the intent of the parties. (Id. at pp. 791-792.) The second constraint is the common law requirement that the terms of a contract be sufficiently definite. A contract that can be amended with complete freedom by less than all parties risks being found illusory. (Id. at p. 797.) Finally, every contract has an implied covenant of good faith and fair dealing that restricts the power of the parties to act in a manner contrary to the interests of other parties to the contract. The amending party's duty to comply with this covenant limits the scope of the amendments it can adopt. (Id. at p. 796.) After discussing a variety of decisions and the foregoing legal constraints, the court concluded the issue before it was ultimately one of contract interpretation and construed the card agreement to determine what the parties intended when they agreed the bank could modify the "terms" of the card agreement. (Badie, supra, 67 Cal.App.4th at pp. 798-800.) The court ultimately held, for several reasons, the parties had not intended to give the bank the authority to amend the agreement to eliminate the right to have disputes resolved in the civil justice system. (Id. at pp. 801-804.) In sum, a bank attempted to unilaterally impose an arbitration provision on its customers by sending them bill stuffers notifying them of a change in terms. The bank asserted it had the right to add the arbitration provision to the customer agreements because it had retained the right to unilaterally change the terms of those agreements. The court struck down the arbitration clause, having determined that the original customer agreements did not contemplate the addition of any new terms of that nature. ( Id. at p. 803.)