Under the Dodd-Frank Act, 12 U. S. C.§ 25b(b)(1)(B), the National Bank Act preempts state law, as applied to a national bank, only if (a) the state law discriminates in favor of state banks and against national banks, or (b) “prevents or significantly interferes with the exercise by the national bank of its powers,” the standard articulated in Barnett Bank of Marion County, N. A. v. Nelson, 517 U. S. 25 (1996). The Barnett Bank test does not draw any bright line but instead requires a careful analysis of the state law’s practical effect on national banks as analyzed in the five prior US Supreme Court decisions that Barnett Bank discussed in arriving at its test. Here, the Second Circuit failed to engage in that required analysis in holding NY’s statute requiring payment of interest on mortgage escrow accounts was preempted. Hence, its decision is vacated and remanded for re-determination under the proper Barnett Bank standard.