Summary

Portrait of Roger B. Taney Roger B. Taney Fremont v. United States — Opinion of the Court

And the first point to be decided is, whether the grant vested in Alvarado any present and immediate interest; and, if it did, then, secondly, whether any thing done or omitted to be done by him, during the existence of the Mexican government in California, forfeited the interest he had acquired, and revested it in the government? For if, at the time the sovereignty of the country passed to the United States, any interest, legal or equitable, remained vested in Alvarado or his assigns, the United States are bound in good faith to uphold and protect it.
Source: Wikisource

Portrait of Roger B. Taney Roger B. Taney Fremont v. United States — Opinion of the Court

At all events, they never acted on it. And the omission or inability of the public authorities to perform their duty, cannot, upon any sound principle of law or equity, forfeit the property of the individual to the State. It undoubtedly disabled him from obtaining what is called a definitive title, showing that all the conditions had been performed; but it could not devest him of the right of property he had already acquired by the original grant, and revest it in the State.
And certainly no delay is chargeable to Alavardo or Fremont after California was subjected to the American arms.
Source: Wikisource

Portrait of Roger B. Taney Roger B. Taney Fremont v. United States — Opinion of the Court

The Mexican government, if it had regained the power, and it had been its policy to prevent the alienation of real estate, might have treated the sale by Alvarado as a violation of its laws; but it becomes a very different question when the American government is called on to execute the Mexican law. And it can hardly be maintained that an American citizen, who makes a contract or purchases property under such circumstances, can be punished in a court of the United States with the penalty of forfeiture, when there is no law of congress to inflict it.
Source: Wikisource

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