In the case of The Mayor, Aldermen, and Commonalty of the City of New York v. George Miln, the Supreme Court was tasked with determining whether a state law passed in 1811 that allowed for an individual to be held liable for damages caused by their vessel colliding with another vessel applied retroactively. At issue was whether or not this law could be used to hold George Miln responsible for a collision between his ship and another ship that occurred prior to 1811. The court ultimately ruled against Miln on the grounds that he had been given sufficient notice regarding potential liability under such laws when he purchased his vessel in 1812 and therefore should have known about them even if they were not yet codified into law at the time of his purchase. As such, it was determined that these laws did indeed apply retroactively in this instance.

In the case of The Mayor, Aldermen, and Commonalty of the City of New York v. George Miln, the Supreme Court was asked to decide whether a state law that authorized cities to impose taxes on vessels entering their ports was constitutional. The majority opinion held that such laws were unconstitutional because they violated Congress’s exclusive power over interstate commerce under Article I Section 8 Clause 3 of the Constitution. However, Justice McLean dissented from this decision and argued that states had concurrent powers with Congress in regulating commerce within their borders. He reasoned that since ships are considered property while in port or navigating waters within a state's jurisdiction then it is reasonable for states to have authority over them through taxation as long as those taxes do not interfere with federal regulations concerning navigation or trade between different states. Furthermore he noted how other courts had previously upheld similar laws without any challenge from Congress so there must be some validity behind them even if they do conflict with Congressional power over interstate commerce