Does the Elastic Clause contradict the 10th Amendment?

Answer 1

There is no absolute answer to that question because much depends on the courts' interpretation of both the law and the Constitution, and these interpretations change over time.

Use of the Necessary and Proper Clause (aka Elastic Clause) of Article I, Section 8, overrules the Tenth Amendment (aka State sovereignty, statutes, ordinances, etc.) on the basis of the Article VI, Section 2, Supremacy Clause, provided whatever federal law was enacted on the basis of that clause is upheld as constitutional.

In other words, if someone with standing challenges a federal law and (assuming the case goes through the full appellate process) the US Supreme Court determines it serves a legitimate government function that can be justified under the Constitution, then the federal law can't be canceled out by the Tenth Amendment.

This doesn't contradict the Tenth Amendment, but does limit its application. The federal courts don't automatically support federal legislation, however; there have been many instances that the courts have found in favor of the States.

Article VI, Section 2 (Supremacy Clause):

"This Constitution, and the laws of the United States which shall be made in pursuance thereof; and all treaties made, or which shall be made, under the authority of the United States, shall be the supreme law of the land; and the judges in every state shall be bound thereby, anything in the Constitution or laws of any State to the contrary notwithstanding."

Tenth Amendment:

"The powers not delegated to the United States by the Constitution, nor prohibited by it to the states, are reserved to the states respectively, or to the people."