In the case of American Farm Lines v. Black Ball Freight Service et al., 1969, the U.S. Supreme Court ruled that courts should not interfere with administrative agencies' decision-making processes unless there is a clear violation of statutory or constitutional rights. The case arose when American Farm Lines (AFL) sought to expand its trucking operations and applied for permission from the Interstate Commerce Commission (ICC). Competing companies, including Black Ball Freight Service, opposed this expansion on grounds that AFL had failed to provide adequate notice and hearing as required by law before making such decisions. However, the ICC approved AFL's application without holding hearings or requiring formal findings. The opposing companies took their grievances to court where they won at both district level and in appeals court which held that procedural requirements were violated by ICC’s approval process without a hearing or formal findings. However, upon reaching Supreme Court it was decided in favor of AFL stating that if an agency has been granted discretion over certain matters by Congress then judiciary should refrain from interfering unless there is evident breach of statutory or constitutional provisions.

In the dissenting opinion for American Farm Lines v. Black Ball Freight Service, Justice Harlan disagreed with the majority's decision to overturn a ruling by the Interstate Commerce Commission (ICC). He argued that courts should defer to administrative agencies like ICC when they interpret their own regulations unless there is compelling evidence of error. In this case, he saw no such evidence and believed that ICC had acted within its authority in approving certain freight rates without holding formal hearings. He also expressed concern about potential negative impacts on regulatory efficiency if courts routinely second-guess agency decisions in this way.