Who was the first Supreme Court Justice and strengthened the power of the Supreme Court?

John Marshall, who served as the Chief Justice of the United States from 1801 to 1835, played a pivotal role in establishing the Supreme Court as a powerful and independent branch of the federal government. His decisions emphasized the principle of judicial review, which allows the Court to determine the constitutionality of laws and actions taken by Congress and the executive branch. This principle was solidified in the landmark case Marbury v. Madison in 1803, where Marshall declared that it is the duty of the judiciary to say what the law is, reinforcing the judiciary's authority and its role as a check on the other branches of government. Through his tenure, Marshall's interpretations of the Constitution helped to shape the balance of power in the United States, making him a foundational figure in American legal history.