delivered the opinion of the Court.
On April 28, 1936, a check was drawn on the Treasurer of the United States through the Federal Reserve Bank of Philadelphia to the order of Clair A. Barner in the amount of $24.20. It was dated at Harrisburg, Pennsylvania, and was drawn for services rendered by Barner to the Works Progress Administration. The check was placed in the mail addressed to Barner at his address in Mackeyville, Pa. Barner never received the check. Some unknown person obtained it in a mysterious manner and presented it to the J. C. Penney Co. store in Clearfield, Pa., representing that he was the payee and identifying himself to the satisfaction of the employees of J. C. Penney *365 Co. He endorsed the check in the name of Barner and transferred it to J. C. Penney Co. in exchange for cash and merchandise. Barner never authorized the endorsement nor participated in the proceeds of the check. J. C. Penney Co. endorsed the check over to the Clearfield Trust Co. which accepted it as agent for the purpose of collection and endorsed it as follows: “Pay to the order of Federal Reserve Bank of Philadelphia, Prior Endorsements Guaranteed.” 1 Clearfield Trust Co. collected the check from the United States through the Federal Reserve Bank of Philadelphia and paid the full amount thereof to J. C. Penney Co. Neither the Clearfield Trust Co. nor J. C. Penney Co. had any knowledge or suspicion of the forgery. Each acted in good faith. On or before May 10, 1936, Barner advised the timekeeper and the foreman of the W. P. A. project on which he was employed that he had not received the check in question. This information was duly communicated to other agents of the United States and on November 30, 1936, Barner executed an affidavit alleging that the endorsement of his name on the check was a forgery. No notice was given the Clearfield Trust Co. or J. C. Penney Co. of the forgery until January 12, 1937, at which time the Clearfield Trust Co. was notified. The first notice received by Clearfield Trust Co. that the United States was asking reimbursement was on August 31, 1937.
This suit was instituted in 1939 by the United States against the Clearfield Trust Co., the jurisdiction of the federal District Court being invoked pursuant to the provisions of § 24 (1) of the Judicial Code, 28 U. S. C. § 41 (1). The cause of action was based on the express guaranty of prior endorsements made by the Clearfield Trust Co.
*366
J. C. Penney Co. intervened as a defendant. The case was heard on complaint, answer and stipulation of facts. The District Court held that the rights of the parties were to be determined by the law of Pennsylvania and that since the United States unreasonably delayed in giving notice of the forgery to the- Clearfield Trust Co., it was barred from recovery under the rule of
Market Street Title & Trust Co.
v.
Chelten Trust Co.,
We agree with the Circuit Court of Appeals that the rule of
Erie R. Co.
v.
Tompkins,
In our choice of the applicable federal rule we have occasionally selected state law. See
Royal Indemnity Co.
v.
United States, supra.
But reasons which may make state law at times the appropriate federal rule are singularly inappropriate here. The issuance of commercial paper by the United States is on a vast scale and transactions in that paper from issuance to payment will commonly occur in several states. The application of state law, even without the conflict of laws rules of the forum, would subject the rights and duties of the United States to exceptional uncertainty. It would lead to great diversity in result's by making identical transactions subject to the vagaries of the laws of the several states. The desirability of a uniform rule is plain. And while the federal law merchant, developed for about a century under the regime of
Swift
v.
Tyson,
United States
v.
National Exchange Bank,
The
National Exchange Bank
case went no further than to hold that prompt notice of the discovery of the forgery was not a condition precedent to suit. It did not reach the question whether lack of prompt notice might be a defense. We think it may. If it is shown that the drawee on learning of the forgery did not give prompt notice of it and that damage resulted, recovery by the drawee is barred. See
Ladd & Tilton Bank
v.
United States,
Affirmed.
Notes
Guarantee of all prior indorsements on presentment for payment of such a check to Federal Reserve banks or member bank depositories is required by Treasury Regulations. 31 Code of Federal Regulations § 102.32, § 202.33.
Various Treasury Regulations govern the payment and endorsement of government checks and warrants and the reimbursement of the Treasurer of the United States by Federal Reserve banks and member bank depositories on payment of checks or warrants bearing *367 a forged endorsement. See 31 Code of Federal Regulations §§ 202.0, 202.32-202.34. Forgery of the check was an offense against the United States. Criminal Code § 148, 18 U. S. C. § 262.
We need nut determine whether the guarantee of prior endorsements adds to the drawee’s rights. See Brannan’s Negotiable Instruments Law (6th ed.) pp. 330-331, 816-817;
First National Bank
v.
City National Bank,
