Here's the "dope" -- ha-ha -- from the About USADA on the web site:
'The U.S. Anti-Doping Agency (USADA) is the national anti-doping organization for the Olympic movement in the United States. The U.S. Congress recognized USADA as "the official anti-doping agency for Olympic, Pan American and Paralympic sport in the United States."'
It is not a government agency. The "recognition" by the Congress is a joint resolution not binding on any outside parties. Its power stems, I guess, from the fact that other organizations -- the IOC, for example -- are likely to recognize its results.
If I understand the situation -- legal eagles, SOS -- the USADA offered him some form of binding arbitration to avoid being public roasted with its accusations. If he had accepted binding arbitration, then he would be in a situation with discovery, testimony, sworn statements, etc. Armstrong thought it was a one-sided situation and that it was best to duck it entirely. "He chose to be a martyr," said one cycling official approvingly.
The USADA issued the following statement: "USADA announced today that Lance Armstrong has chosen not to move forward with the independent arbitration process and as a result has received a lifetime period of ineligibility and disqualification of all competitive results from August 1, 1998 through the present, as the result of his anti-doping rule violations stemming from his involvement in the United States Postal Service (USPS) Cycling Team Doping Conspiracy (USPS Conspiracy)."
I am not sure where the "disqualification" authority comes from. It would seem to require independent actions of other entities.
Anyway, stay tuned.