Thompson v. Railroad Companies was a United States Supreme Court case that was decided in 1867. The case involved a dispute between the plaintiff, Thompson, and several railroad companies. Thompson had been hired by the railroad companies to construct a bridge over the Mississippi River. Thompson had completed the bridge, but the railroad companies refused to pay him for his work. Thompson sued the railroad companies, arguing that they had breached their contract with him. The Supreme Court agreed with Thompson and held that the railroad companies had breached their contract with him. The Court ordered the railroad companies to pay Thompson the amount that he was owed for his work. The decision in Thompson v. Railroad Companies established that a contract must be honored by both parties, and that a breach of contract can result in damages being awarded to the non-breaching party. This case is still cited today as an example of the importance of honoring contracts.

In Thompson v. Railroad Companies, the Supreme Court was asked to decide whether a state law that allowed railroad companies to charge higher rates for short-hauls than long-hauls violated the commerce clause of the Constitution. The majority opinion held that it did not violate this clause and upheld the law. However, in his dissenting opinion Justice Field argued that allowing states to regulate interstate commerce in such a manner would lead to an unequal burden on interstate trade and could potentially create chaos among different states’ regulations. He further argued that Congress should be given exclusive power over regulating interstate commerce as outlined by Article I Section 8 of the Constitution which gives Congress authority “to regulate Commerce with foreign Nations, and among several States." In conclusion, Justice Field believed that allowing individual states to impose their own laws regarding transportation rates would interfere with free trade between states and thus violate constitutional principles set forth by our founding fathers.