The statement that best assesses the impact of the cases Marbury v. Madison and McCulloch v. Maryland on the Constitution is:
Both cases increased the powers of the federal government.
Marbury v. Madison established the principle of judicial review, enhancing the power of the judiciary, while McCulloch v. Maryland affirmed the supremacy of federal laws over state laws and allowed for a broader interpretation of federal powers. Together, they reinforced the authority of the federal government within the constitutional framework.