Ex parte Dubuque and Pacific Railroad was a case heard by the United States Supreme Court in 1863. The railroad had been granted permission to build a bridge across the Mississippi River, but it was challenged by steamboat owners who argued that they would be unable to navigate safely under such an obstruction. The court held that Congress had exclusive authority over navigable waters of the United States, including those within state boundaries, and thus could grant rights for bridges or other obstructions on them without interference from states. Furthermore, since Congress had already authorized construction of this particular bridge through its chartering of the railroad company itself, no further approval from any state government was necessary. This decision established federal supremacy over interstate navigation and commerce as well as reaffirmed congressional power to regulate these matters under Article I Section 8 Clause 3 (the Commerce Clause) of the U.S Constitution

In Ex Parte Dubuque and Pacific Railroad, the Supreme Court was asked to decide whether a railroad company had acquired title to land by virtue of an act of Congress. The majority opinion held that the railroad did not have such title because it failed to comply with certain conditions set forth in the act. Justice Field dissented from this decision, arguing that while there may have been some technical deficiencies in how the railroad went about acquiring its rights under the law, these were minor issues which should not be used as a basis for denying them their property rights. He argued that if Congress intended for strict compliance with all conditions then they would have made those requirements clear in their legislation. Furthermore, he noted that since no one else had any claim on this land prior to its acquisition by the railroad company, it was unfair and unjustified for them now to be deprived of what is rightfully theirs due solely to minor discrepancies or oversights on their part.