Eleazer F. Backus was a defendant in a copyright infringement case in the United States Supreme Court in 1849. The case, titled Eleazer F. Backus, Plaintiff in Error, v. William Gould and David Banks, who sue as well for the United States as themselves, involved Gould and Banks suing Backus for allegedly infringing on their copyright of nine volumes of Cowen's Reports and the first three volumes of Wendell's Reports.
The case made it to the Supreme Court on a writ of error from the Circuit Court of the United States for the Northern District of New York. The case was a qui tam action, which is a type of lawsuit brought by a private citizen on behalf of the government. In this case, Gould and Banks brought the lawsuit against Backus for the United States as well as themselves. The case centered around the number of infringing copies that the accused had in their possession, with the Supreme Court ultimately holding that the Copyright Act of 1831 required courts to award damages based on the number of copies found in the accused's possession, not the number of infringing copies that they ever printed.