The Fannie was a case heard by the United States Supreme Court in 1870. The case involved a dispute between the owners of the Fannie, a steamboat, and the owners of the wharfboat, the St. Louis. The Fannie had been moored to the St. Louis for several days, and the owners of the St. Louis claimed that the Fannie had caused damage to the wharfboat. The owners of the Fannie argued that they were not liable for the damage, as they had not caused it. The Supreme Court ultimately ruled in favor of the owners of the Fannie. The Court held that the owners of the Fannie were not liable for the damage to the St. Louis, as they had not caused it. The Court reasoned that the damage was caused by the natural forces of the river, and not by the Fannie. The Court also noted that the Fannie had been moored to the St. Louis for several days, and that the owners of the St. Louis had not taken any steps to protect the wharfboat from the natural forces of the river. The Fannie case is an important precedent in the law of torts, as it established that a person or entity is not liable for damages caused by natural forces, even if they are moored to the property that is damaged. This case is still cited today in cases involving liability for damages caused by natural forces.

In The Fannie, the Supreme Court was asked to decide whether a vessel named "The Fannie" could be considered an American-built ship. In a 5-4 decision, the majority of justices held that it did not qualify as such because its hull had been built in England and only assembled in America. Justice Field dissented from this opinion, arguing that Congress had intended for vessels like The Fannie to be treated as American ships when they were substantially constructed within U.S. borders regardless of where their components originated from. He argued that since most of the work on The Fannie was done in America and it satisfied all other requirements set out by Congress, it should have been classified as an American-built vessel under existing law. Furthermore, he noted that if his interpretation wasn't accepted then many similar vessels would face unfair consequences due to technicalities rather than substance which would ultimately harm commerce between nations and states alike.