Armstrong v. American Exchange National Bank of Chicago was a case heard by the Supreme Court of the United States in 1925. The case involved a dispute between the bank and the Armstrongs, a family of farmers in Illinois. The Armstrongs had borrowed money from the bank to purchase a farm, and had agreed to pay the loan back with interest. However, the Armstrongs had failed to make the payments on time, and the bank had sued them for the unpaid debt. The Supreme Court ruled in favor of the bank, finding that the Armstrongs had breached their contract with the bank and were liable for the unpaid debt. The Court also held that the bank had the right to foreclose on the farm if the Armstrongs failed to make the payments. The Court further held that the bank was entitled to recover its costs and attorney's fees from the Armstrongs. The decision in Armstrong v. American Exchange National Bank of Chicago established that banks have the right to foreclose on property if a borrower fails to make payments on a loan. It also established that banks are entitled to recover their costs and attorney's fees from the borrower in such cases. This decision has been cited in numerous subsequent cases involving loan defaults and foreclosure.

In the dissenting opinion of Armstrong v. American Exchange National Bank of Chicago, Justice Black argued that the majority’s decision was wrong and should be overturned. He believed that Congress had not intended for national banks to have such broad powers when it passed the National Banking Act in 1864, which allowed them to charge interest rates higher than those set by state law. The dissent argued that this interpretation would lead to an “absurd result” because it would allow a single bank or group of banks to control all banking activities within a state and thus create monopolies on credit services. Furthermore, he noted that if Congress wanted national banks to have such power over local laws they could easily pass legislation granting them such authority but instead chose not too do so as evidenced by their silence on the matter since 1864. In conclusion, Justice Black felt strongly that allowing national banks this kind of power over local laws was beyond what Congress had originally intended with its passage of the National Banking Act in 1864 and therefore should be overturned by Supreme Court precedent