United States v. Mora was a United States Supreme Court case that dealt with the issue of whether a defendant could be convicted of a crime if the indictment did not specify the exact date of the offense. The defendant, Mora, was charged with the crime of unlawfully entering the United States without permission. The indictment did not specify the exact date of the offense, but instead stated that it occurred "on or about" a certain date. The Supreme Court held that the indictment was sufficient to sustain a conviction. The Court reasoned that the phrase "on or about" was sufficient to give the defendant notice of the charge against him and to enable him to prepare a defense. The Court also noted that the exact date of the offense was not necessary to prove the crime, as long as the evidence showed that the offense occurred within a reasonable time of the date specified in the indictment. In conclusion, the Supreme Court held that an indictment that does not specify the exact date of the offense is sufficient to sustain a conviction, as long as the evidence shows that the offense occurred within a reasonable time of the date specified in the indictment.

In United States v. Mora, the Supreme Court was asked to decide whether a Mexican citizen who had been convicted of murder in Mexico and then escaped from prison could be extradited back to Mexico by the United States government. The majority opinion held that extradition was permissible under international law and treaties between the two countries, but Justice Field dissented on grounds that such an action would violate due process rights guaranteed by the Fifth Amendment of the U.S Constitution. He argued that since no treaty existed between Mexico and America at this time which specifically allowed for extradition, it should not be permitted as it would amount to a deprivation of liberty without due process of law or any other legal authority recognized in American jurisprudence. Furthermore, he noted that even if there were such a treaty in place, its provisions must still comply with constitutional requirements before they can be enforced within U.S borders - something which did not appear to have occurred here given how little evidence had been presented regarding Mora's guilt or innocence prior to his extradition request being granted by President Grant's administration