In the United States v. Mauro et al., 1977, the Supreme Court ruled on a case involving extradition and federal custody of prisoners. The respondents, two state prisoners who were also subject to detainers lodged by Italy under an extradition treaty with the U.S., argued that their transfer from state to federal custody violated Article IV(e) of the Interstate Agreement on Detainers (IAD). They claimed this article prohibited transfers for purposes other than those listed in its terms. However, the court held that such transfers did not violate IAD as it was intended to prevent abuses associated with detainers' use rather than regulate prisoner's movements between jurisdictions. Furthermore, it clarified that once a request for temporary custody is made under IAD’s terms and honored by receiving State; any subsequent action does not affect its legality or validity.

In the dissenting opinion for United States v. Mauro et al., Justice Brennan, joined by Justices Stewart and Marshall, argued that the majority's interpretation of Article IV(a) of the Treaty was incorrect. They contended that this provision should not be read as a mandatory extradition clause but rather as an agreement between Italy and the U.S to surrender individuals who have been tried in absentia only if both countries consented to such action. The dissent also criticized the majority's reliance on executive interpretations of treaty provisions without considering legislative intent or historical context. Furthermore, they expressed concern about potential violations of due process rights because defendants might be extradited without having an opportunity to challenge their convictions in Italian courts first.