It is possible that the agreement needs to be approved by Congress. The Constitution says that agreements between states need Congress to approve. However, the U.S. Supreme Court says that this is not always true. They talked about that question in the court case "Virginia v. Tennessee" and others. They decided the only agreements that need approval are those that threaten the authority of the U.S. government. Every Vote Equal says that the NPVIC cannot threaten the authority of the U.S. government, because the Constitution lets states decide how to give out their electoral votes. Derek Muller does not agree. He argues that the NPVIC affects the U.S. government system, and so it needs approval. Ian Drake says that Congress is not allowed to approve the agreement. Those who support the NPVIC do not agree. They do not think the agreement needs approval from Congress, but they plan to ask for this approval in any case.