In the United States Supreme Court case of The United States v. Andres Pico, the court was asked to decide whether a treaty between Mexico and the United States had been violated by California land grants made by Mexican General Andres Pico in 1845. The U.S., as appellant, argued that these grants were invalid because they conflicted with an earlier Treaty of Guadalupe Hidalgo which ceded California from Mexico to the U.S.. In its decision, however, the court found that since no one had challenged or questioned these land grants prior to their ratification in 1851—and since both parties involved (Mexico and California) had accepted them—the grantees should be allowed to keep their lands under existing law at that time. Furthermore, it held that any claims against those who received such titles must be brought before state courts rather than federal ones due to lack of jurisdiction on behalf of Congress over private property rights within states’ borders. Ultimately this ruling established precedent for future cases involving similar issues regarding treaties and private property rights within states’ boundaries

In the United States v. Andres Pico, the Supreme Court was tasked with deciding whether a land grant issued by Mexico to Pico in 1845 was valid under U.S. law after California became part of the Union in 1850. The majority opinion held that it was not and that Congress had exclusive authority over public lands within its borders, regardless of any prior grants made by foreign governments or other entities before statehood occurred. Justice Grier dissented from this decision on two grounds: first, he argued that there were no laws passed by Congress which expressly prohibited such pre-statehood grants; second, he contended that even if there were such laws they would be unconstitutional as they would violate Article IV Section 3 of the Constitution which states “The Congress shall have Power to dispose of and make all needful Rules and Regulations respecting Property belonging to the United States” – meaning only property owned by them could be regulated or disposed of at their discretion rather than private property like Pico's land grant from Mexico. He concluded his dissent stating “I am unable to concur in an opinion so contrary both to justice and sound policy."