Judge Ciaffa in the District Court of Nassau found that Chase was permitted to apply its home interest rates (Delaware; see 12 USC §85) to the subject credit card accounts pre-litigation, and further observed that Chase behaved in applying New York's 9% maximum rate post-commencement.
J. Ciaffa stated, "a national bank with a home office in the state may apply the law of that state where it "conducts virtually all of its credit card operations in and from its main office state."
The court accepted as admissible and probative Chase's Vice President who swore by affirmation to attach relevant card member agreements and monthly statements that showed periodic adjustment of interest charges.
Keep in mind that this inquest proceed with an unrepresented litigant who did not challenge Chase at the inquest. Had he consulted The Langel Firm, perhaps he would have successfully challenged the admissibility of the evidence.