In any action by a card issuer to enforce liability for the use of a credit card, the burden of proof is upon the card issuer to show that the use was authorized or, if the use was unauthorized, then the burden of proof is upon the card issuer to show that the conditions of liability for the unauthorized use of a credit card, as set forth in subsection (a), have been met.
15 U.S. Code § 1643 - Liability of holder of credit card
1980—Subsec. (a). Pub. L. 96–221 revised existing provisions into pars. (1) and (2) and, as so revised, in par. (1) made changes in structure and phraseology and revised means of notice and verification, and in par. (2) made changes in phraseology.
Amendment by Pub. L. 96–221 effective on expiration of two years and six months after Mar. 31, 1980, with all regulations, forms, and clauses required to be prescribed to be promulgated at least one year prior to such effective date, and allowing any creditor to comply with any amendments, in accordance with the regulations, forms, and clauses prescribed by the Board prior to such effective date, see section 625 of Pub. L. 96–221, set out as a note under section 1602 of this title.