King is especially incensed that an American publisher, Knopf, has entered into a book deal with Assange (who is reportedly receiving over a million dollars for his memoir); and if he is now blacklisted, you could conceivably break the law merely by buying his book, or contributing to a WikiLeaks defense fund. In other words, King is not simply targeting Assange and Wikileaks; he is targeting all of us -- every American citizen and company. In his view, even a paying consumer of information and ideas from WIkiLeaks or Assange is collaborating in terrorism.
This doesn't mean that every WikiLeaks consumer or supporter would actually be prosecuted for every trivial transaction. It does mean that if you're targeted by the Administration as a political threat, it has one more weapon in its arsenal to use against you. And, while the expansive maze of federal laws may make ordinary, generally law abiding people theoretically liable to prosecution anyway (as my friend Harvey Silverglate has written, most people probably commit "three felonies a day"), the power afforded by blacklisting laws is particularly arbitrary and unaccountable. You can be blacklisted without due process, without notice of an investigation or a chance to defend yourself.
On the other hand, you can violate blacklists (and there are several) with impunity if your prosecution would be politically inconvenient. As David Cole pointed out in a New York Times op-ed, Rudy Guiliani and several high ranking former Bush Administration officials (including former Attorney General Mukasey) met with a blacklisted organization late last year, but -- good for them --their First Amendment rights seem secure.
Blacklisting is enabled by a network of federal statutes and executive orders, which requires study to begin to understand. (I doubt many members of Congress can explain it.) Complicated, obscure, and arbitrary, with an incredibly wide reach, this is a legal regime practically designed to be abused. It represents the politicization of law, for which both parties are responsible; and it's a lot more tyrannical than health care reform.
UPDATE: The Treasury Department has declined Congressman King's request
to blacklist WikiLeaks and Assange, according to The Hill, citing a lack
of evidence "at this time."