From the Article wrote:Al-Awlaki, 39, who is a U.S. citizen, has clearly gone beyond mild criticism of his country, according to the Obama administration, which in naming him a global terrorlst has made him a target for assassination by U.S. forces or CIA drones. The designation was a recognition that al-Awlaki has risen in the ranks of anti-Western Islamic extremism and become a mortal enemy, a danger to America's national security on a par with 9/11 mastermind Osama bin Laden.
The Smith Act is still on the books, but its invocation in a case like this one would be a stretch. Even so, it's not necessarily punishable by death, and certainly does not justify a suspension of due process. If you were to link him directly to the Taliban or al-Queda in Iraq, both designated as enemies of the state, then it falls under the broad powers afforded the CIA as part of the war policies, but otherwise no sir.
If I was POTUS and I could get dirt on Al-Awlaki that would clearly implicate them in one or more actual crimes, I'd have him captured and prosecuted (he IS a citizen of the U.S.). If I saw him meeting with members of a known and documented enemy of the state, I'd off him and label it collateral damage.