this is from the Wikipedia entry on IMPLIED POWERS
Part of both the genius and success of the Constitution is that it allows for the evolution of government as the nation changes. This is accomplished through reinterpretation of sections like the General Welfare clause and the Necessary and Proper Clause. It was not by accident that such clauses were left open ended. The ability of the Constitution to be amended also allows for change as the nation changes.
Quote: "Implied powers" are powers not given to the government directly through the constitution, but are implied. These powers fall under the Elastic Clause in Section 8 of Article 1 of the U.S. Constitution. This document lets the government create “necessary and proper†programs/laws and retain them, such as creating the Air Force. The Air Force is an implied power because the constitution did not give the power of the Air Force to the federal government, because airplanes didn’t even exist.
"Implied powers" are those powers authorized by a legal document which, while not stated, are deemed to be implied by powers expressly stated. When George Washington asked Alexander Hamilton to defend the constitutionality of the measure against the protests[1] of Thomas Jefferson, James Madison, and Attorney General Edmund Randolph, Hamilton produced what has now become the classic statement for implied powers.[2] Hamilton argued that the sovereign duties of a government implied the right to use means adequate to its ends. Although the United States government was sovereign only as to certain objects, it was impossible to define all the means which it should use, because it was impossible for the founders to anticipate all future exigencies. Hamilton noted that the "general welfare clause" and the "necessary and proper" clause gave elasticity to the constitution. Hamilton won the argument with Washington, who signed his Bank Bill into law.
Even Hamilton's adversary, Thomas Jefferson, used the principle to justify his Louisiana Purchase in 1803. Later, directly borrowing from Hamilton, Chief Justice John Marshall invoked the implied powers of government in the court decision of McCulloch v. Maryland. This was used to justify the denial of the right of a state to tax a bank, the Second Bank of the United States, using the idea to argue the constitutionality of the United States Congress creating it in 1816.
In the case of the United States government, implied powers are the powers exercised by Congress which are not explicitly given by the constitution itself.