In the United States National Bank et al. v. Chase National Bank et al., 1946, the U.S Supreme Court was tasked with deciding whether a national bank could be sued in federal court by non-residents of the state where it is located, based on diversity jurisdiction. The case arose when United States National Bank of Portland (Oregon) and its shareholders filed suit against Chase National Bank and others in New York for alleged breach of fiduciary duty related to certain securities transactions. The defendants argued that under federal law, a national bank can only be sued in the district or county where it is established. The Supreme Court ruled in favor of Chase National Bank, holding that for purposes of diversity jurisdiction, a national banking association is "located" only in the state designated as its main office location according to its articles of association - not every state where it may have branch offices or do business. Therefore, since both parties were considered residents within New York State due to their operations there; no diversity existed between them which would allow for federal subject matter jurisdiction over this dispute.

In the dissenting opinion for United States National Bank et al. v. Chase National Bank et al., Justice Frankfurter expressed concern over the majority's interpretation of Section 7 of the Clayton Act, arguing that it was too broad and could potentially stifle legitimate business growth and competition. He argued that not all acquisitions leading to a decrease in competition are necessarily detrimental or illegal under this act, especially if they also lead to increased efficiency or other benefits. Furthermore, he disagreed with the majority's view on potential competition theory - which suggests that even companies not currently competing can be seen as competitors because they might enter into each other’s markets in future - stating it is speculative and lacks concrete evidence. He believed such an approach would create uncertainty for businesses planning mergers or acquisitions due to its subjective nature.