The correct response regarding the impact of the ruling in Cohens v. Virginia (1821) on the federal government is:
It established that the Supreme Court would judge all cases involving the U.S. Constitution.
Cohens v. Virginia reinforced the authority of the Supreme Court to review state court decisions regarding federal law and the Constitution, affirming the role of the Supreme Court as the final arbiter in constitutional matters. This case was significant in establishing the supremacy of federal law over state law and solidifying the judiciary's power within the federal government.