In the United States Supreme Court case of The United States v. Andres Castillero, the court was asked to decide whether a Mexican citizen could be held liable for debts incurred in California prior to its admission into the Union as a state. The appellant argued that since California had not yet been admitted into the Union at the time of contract formation, it did not have authority over foreign citizens and thus they were exempt from liability under US law. However, after considering both sides’ arguments, including those related to international treaties between Mexico and America regarding debt obligations, the court ultimately ruled against Castillero on grounds that he should have known his actions would be subject to US laws once California became part of America. This ruling established an important precedent which has been used in subsequent cases involving contracts formed before states joined or left unions such as during secession periods or when territories become states.

In the case of United States v. Andres Castillero, the Supreme Court was asked to decide whether a Mexican citizen who had been living in California since 1845 could be convicted for failing to register as an alien under federal law. The majority opinion held that Castillero did not have standing because he was not subject to the jurisdiction of Congress and therefore could not be convicted under this statute. However, Justice Grier dissented from this decision on two grounds: firstly, that it should have been up to a jury rather than the court itself to determine if Castillero was subject or not; and secondly, that even if he were found by a jury not to be so subject then his conviction should still stand due its being based upon other valid laws which applied equally regardless of citizenship status. In conclusion, Justice Grier argued strongly against what he saw as an overly broad interpretation of Congressional power over aliens residing within US borders.