32 HARVARD LAW REVIEW the seller-addressee has done anything toward performance, and so procures the issuer to attempt cancellation of the letter. It would seem that the letter might be canceled on the offer theory, even though it is stated to be irrevocable, since if we concede that a collateral agreement not to revoke an offer will make it irrev- ocable, there is nevertheless no consideration here for such agree- ment. Also it would seem that the letter under the theory of its being an acknowledgment of money had to addressee's use, might be canceled, unless the addressee can meet the burden of showing that the issuer actually received the money to his use, for the letter would be an admission only and no estoppel would be available. A contrary result would be reached on the theory of the letter as a notification of a contract between holder and issuer for the benefit of addressee, in jurisdictions where it is held that there can be no rescission by the contracting parties after the third-party benefi- ciary has been notified. This sort of situation calls for a theory of the letter of credit as a self-sufficing instrument of the law merchant. What is the position of the issuer in case of controversies between the buyer-holder and the seller-addressee as to performance of the sales contract and construction of its conditions? The issuer could hardly become involved in such controversies nor incur risk be- cause thereof if the letter were drawn with judgment, and liability thereunder were expressly made to depend on a few plain simple conditions. But this question may easily become important under some of the forms in current use which seem to incorporate the contract by reference and so make its terms conditions of the letter. If the issuer is in the position of one who has received money from A to the use of B upon a condition, it is obvious that circumstances may arise in which B will claim the money on the ground that the condition has been fulfilled while A will claim it on the ground that the condition has failed. In that event there is a typical case for interpleader, which would afford the issuer full protection were both holder and addressee within the jurisdiction. As the holder is usually abroad, the case is not so simple. But could not the issuer bring his bill of interpleader against the ad- dressee and holder in a court where he could reach addressee and by notifjdng holder obtain a decree which would at least settle the rights of the addressee and bind the holder so far as the domestic
