Final Answer:
Under Chief Justice John Marshall, Supreme Court decisions tended to: a) Expand federal power.
Step-by-step explanation:
During Chief Justice John Marshall's tenure (1801-1835), the Supreme Court played a pivotal role in shaping the interpretation of the United States Constitution. Marshall was a strong advocate for a strong and centralized federal government. His decisions consistently favored the expansion of federal power. One landmark case that exemplifies this trend is "McCulloch v. Maryland" (1819). In this case, Marshall asserted the constitutionality of the Bank of the United States and emphasized the supremacy of federal laws over state laws. Marshall's interpretation of the Necessary and Proper Clause in the Constitution allowed for a broad understanding of federal powers, contributing to the expansion of the federal government's authority.
Marshall's decisions also played a crucial role in establishing the principle of judicial review in "Marbury v. Madison" (1803), solidifying the Court's authority to interpret the Constitution and declare acts of Congress unconstitutional. This further enhanced the federal judiciary's role in shaping the legal landscape and maintaining a balance between the federal and state governments. Overall, Chief Justice John Marshall's legacy is marked by a series of decisions that strengthened the authority of the federal government, supporting the final answer that under his leadership, Supreme Court decisions tended to expand federal power.