Which of the following is a restriction on congressional power over the federal courts?

A. The power to create or expand federal courts
B. Judges being constitutionally appointed for life terms
C. The authority of Congress to enact spending and revenue laws
D. The ability to impeach federal judges
D?

No. Impeachment is a power Congress does have. Which RESTRICTS Congressional power?

The correct answer is B. Judges being constitutionally appointed for life terms.

Yes, option D is correct. The ability to impeach federal judges is a restriction on congressional power over the federal courts.

To arrive at this answer, let's review the other options as well:

Option A: The power to create or expand federal courts is actually within the constitutional authority of Congress. They have the power to establish and organize the federal judiciary system.

Option B: Judges being constitutionally appointed for life terms is a relevant characteristic of the federal court system but not specifically a restriction on congressional power.

Option C: The authority of Congress to enact spending and revenue laws is also not a restriction on congressional power over the federal courts. While Congress has the power to regulate the budget of the federal courts, it does not limit their power over the judiciary.

On the other hand, option D states that Congress has the ability to impeach federal judges. This means that if judges engage in misconduct or abuse of power, Congress can initiate impeachment proceedings to remove them from office. This ability serves as a check on the power of the federal courts and hence restricts congressional power over them.

Therefore, option D is the correct answer.