Question

Why is the Supreme Court's exercise of the power of judicial review so significant, and how did the Court gain that power?

Answer 1

The power of judicial review is the tool that makes the Supreme Court a co-equal branch of government.

In Marbury v. Madison (SCOTUS 1803), the Supreme Court carved out for themselves the power of judicial review, enabling them to review legislative or executive action to see if they were done constitutionally.