The case of California Bankers Association v. Shultz, Secretary of the Treasury, et al., 1973 revolved around the constitutionality of certain provisions in the Bank Secrecy Act (BSA) which required banks to keep records and file reports that have a high degree of usefulness in criminal, tax or regulatory investigations. The California Bankers Association argued these requirements violated their customers' Fourth Amendment rights against unreasonable searches and seizures. However, the Supreme Court ruled that since bank records are business documents maintained by banks in ordinary course of business, they belong to banks not customers; hence there is no legitimate expectation for privacy from customers regarding those documents under Fourth Amendment protections. Furthermore, it was held that requiring such record keeping did not constitute an unreasonable search or seizure as per Fourth Amendment because it didn't involve physical intrusion into any area where person has reasonable expectation for privacy nor does it compel production before a governmental agency without proper judicial oversight.

In the dissenting opinion for California Bankers Association v. Shultz, Justice William O. Douglas argued that the majority's decision to uphold the Bank Secrecy Act violated individual privacy rights and exceeded Congress' constitutional authority under the Commerce Clause. He contended that requiring banks to maintain records of customers' transactions constituted an unreasonable search and seizure in violation of Fourth Amendment protections. Furthermore, he believed this requirement was not necessary or proper for regulating interstate commerce as it did not directly involve commercial activity but rather personal financial matters. He also expressed concern about potential misuse of these records by government agencies without appropriate safeguards against arbitrary or discriminatory enforcement actions.