You would have to ask Tommy Thompson and the Republicans.
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U.S. Shocks with Promise to Back Anti-Smoking Pact
GENEVA (Reuters) - The United States said Sunday it would fully support a global anti-smoking treaty at this week's world health meeting, startling observers by dropping its objections to the pact.
"I'm going to support it -- much to the surprise of many around the world," U.S. Health Secretary Tommy Thompson told journalists on the eve of the World Health Organization's (WHO) annual assembly.
http://www.freerepublic.com/focus/f-news/913738/posts
The UN views the US in the same light that republicans view libertarians.