Boston Mining Company v. Eagle Mining Company is a United States Supreme Court case that was decided in 1885. The case involved a dispute between two mining companies over a mining claim in Colorado. The Boston Mining Company had filed a claim for a mining site in Colorado, but the Eagle Mining Company had also filed a claim for the same site. The Boston Mining Company argued that their claim was valid because they had filed it first, while the Eagle Mining Company argued that their claim was valid because they had made improvements to the site. The Supreme Court ultimately sided with the Boston Mining Company, ruling that the first claimant to file a claim for a mining site has priority over any subsequent claimants. The Court reasoned that the first claimant has the right to the site, and that any improvements made by subsequent claimants do not give them priority over the first claimant. The Court also noted that the first claimant has the right to the site regardless of whether or not they have made improvements to it. This ruling established the principle that the first claimant to file a claim for a mining site has priority over any subsequent claimants.

Justice Field delivered the dissenting opinion in Boston Mining Company v. Eagle Mining Company, arguing that the majority had misinterpreted a key provision of an 1866 mining act which granted exclusive rights to mine certain minerals on public lands. He argued that this interpretation would lead to unjust results and deprive individuals of their property without due process or just compensation. Justice Field further contended that Congress did not intend for such a broad interpretation when it passed the law, as evidenced by its language and legislative history. In addition, he noted that if Congress had intended for such an expansive reading then they would have included more specific language in the statute itself rather than relying on general terms like "exclusive right." Ultimately, Justice Field concluded that while there may be some ambiguity in how one interprets this particular law, it should not be interpreted so broadly as to deny people their property rights without due process or just compensation.