Congress can do anything it wants because the "Commerce Clause" gives them infinite power.
Or at least that's what they say, and sadly the US Supreme Court agrees with.
Of course if this were really true the U.S. Constitution would be a 1 line document that says
The Federal government is all powerful and Congress can pass any and all laws that they damn well feel like.Source
Court refuses to overturn bulletproof vest law
WASHINGTON – The Supreme Court on Monday refused to hear a challenge against a federal law making it illegal for criminals to own bulletproof vests. The appeal had questioned Congress' lawmaking ability under the Commerce Clause.
The high court refused to hear arguments from Cedrick B. Alderman, who was convicted under a federal law making it illegal for convicted criminals to own body armor that has been sold across state lines.
Congress passed that law in 2002, citing its authority under the Commerce Clause to regulate interstate commerce.
Alderman was convicted of armed robbery in 1999. Police caught him with a bulletproof vest in 2005, and he was sentenced to prison for 18 months.
Alderman challenged the law, saying it exceeded Congress' power to regulate interstate commerce under the Commerce Clause. The 9th U.S. Circuit Court of Appeals in San Francisco upheld the conviction and sentence.
The Supreme Court refused to hear Alderman's appeal.
Justice Clarence Thomas and Antonin Scalia said they would have heard the case.
Not hearing the case "threatens the proper limits on Congress' commerce power and may allow Congress to exercise police powers that our Constitution reserves to the states," Thomas said.
The case is Alderman v. United States, 09-1555.