Thelusson et al. v. Smith was a case heard before the United States Supreme Court in 1817. The dispute arose when William Thelusson, an Englishman, died and left his estate to two of his sons who were living in England at the time of his death. His will provided that if either son should die without issue, then their share would pass to the other son's children or descendants as tenants-in-common with those already entitled under the will. When one of these sons died without issue, it was determined that he had no right to dispose of any part of this property by will because he was not a citizen or resident within any state in America at the time he made it; therefore, all rights passed directly from him to his brother’s children upon his death according to American law rather than being subject to British inheritance laws as stated in Thelusson’s original will. Ultimately, after much debate over which country’s laws applied and whether they could be enforced on foreign soil (England), it was decided that since both parties involved were citizens or residents within states located within America at some point during their lifetimes - even though neither party resided there when making their respective wills - American law must take precedence over British law for matters concerning inheritance and disposition of property belonging thereto regardless where such persons may reside outside its borders at any given time thereafter

In Thelusson et al. v. Smith, the Supreme Court was asked to decide whether a contract between two parties could be enforced when it had been made in violation of an English statute that prohibited such contracts from being made without permission from Parliament. Chief Justice Marshall wrote the dissenting opinion, arguing that while he agreed with the majority's conclusion that this particular contract should not be enforced due to its illegality under English law, he disagreed with their reasoning for why it should not be enforced. He argued that since there was no American law prohibiting such contracts and because they were valid at common law prior to any statutory prohibition by England, then they ought still remain valid in America despite any subsequent prohibitions imposed by England on them after the fact. Therefore, according to Chief Justice Marshall's dissent, if a contract is legal under both American and British laws at the time of its formation then it should remain enforceable regardless of any later changes or restrictions placed upon them by either country afterwards.