Question

which of the following is not a way that congress could potentially check the power of the federal courts?
appointing new justices to the courts
refusing to fund the implementation of decisions
jurisdiction - stripping (i.e., limiting the types of cases the courts are allowed to hear)

Explanation:

In the U.S. system of checks and balances, the President appoints federal justices (with Senate confirmation). Congress can refuse to fund court - decision implementation (as funding is a congressional power) and can engage in jurisdiction - stripping (as per its authority over the judiciary's structure).

Answer:

appointing new justices to the courts