I take it you're asking where in the United States Constitution it's said that federal judges have the authority to “invalidate” state or federal laws as unconstitutional. read more
Judicial review, power of the courts of a country to examine the actions of the legislative, executive, and administrative arms of the government and to determine whether such actions are consistent with the constitution. read more
In the United States, judicial review is the ability of a court to examine and decide if a statute, treaty or administrative regulation contradicts or violates the provisions of existing law, a State Constitution, or ultimately the United States Constitution. read more
Judicial review is a process under which executive and (in some countries) legislative actions are subject to review by the judiciary. read more