Congress constrains execution by defining statutory authority, limiting appropriations, requiring reports, structuring offices, confirming principal officers, conducting oversight, and using impeachment for qualifying abuses. Each tool has its own actor and threshold; "congressional check" is not one undifferentiated power.

Separation of powers also limits Congress. Legislators may not appoint principal executive officers, reserve executive removal for themselves, or administer the laws through a legislative veto that bypasses bicameralism and presentment. Congress writes and oversees rules; executive officers carry them out.

A restriction can be legally binding, politically influential, or merely informational. An enacted funding prohibition has legal effect, a hearing may create pressure, and a committee letter may request action without commanding it. Identify the source and consequence before deciding how strongly the executive is constrained.

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