Finally, the Court rejected the argument that not allowing tribes to prosecute nonmembers, those nonmembers would escape prosecution altogether for criminal activity engaged in within tribal boundaries. The federal government retains the power to prosecute felonies that take place on reservations. Tribes retain the power to expel undesirable persons. Tribal authorities may still arrest the nonmember and detain him until he can be handed over to authorities who do have the power to prosecute the nonmember. The tribe pointed out that state authorities can lack the power to prosecute crimes committed by nonmembers on reservations; Arizona, for instance, expressly disclaims this prosecutorial authority. But Congress has allowed states to assume this power, and Arizona is free to take up Congress's invitation. Finally, if the tribes still believed that there remained a "jurisdictional void," despite these options, they could persuade Congress to give it to them.