Investigative power is implied from Congress's legislative responsibilities: lawmakers need information to legislate, appropriate, and evaluate administration. Committees use hearings, document requests, subpoenas, inspectors general, GAO work, and statutory reporting to test whether programs follow law and achieve their purposes.

The inquiry must serve a legitimate legislative function and respect applicable constitutional rights and privileges. A subpoena creates a legal demand but enforcement can require negotiation, chamber action, executive cooperation, or litigation; issuance and compliance are not the same event.

Oversight produces information and political accountability, not criminal judgment. Congress may expose misconduct, revise authority, restrict funds, or impeach when the constitutional standard is met. Prosecutors and courts separately determine criminal charges and liability. Oversight can also be routine: reviewing deadlines, appropriations, and performance data can reveal design problems before misconduct occurs. Effective oversight links evidence to a legislative remedy instead of treating a contentious hearing as an end in itself.

Video lesson: Congressional Decisions: Crash Course Government and Politics #10