The federal government no longer hangs people sentenced to death. Lethal injection is the method used.
I'm sure hanging is still an option in some places,
New Hampshire and Washington are the only states that still have hanging as a method of execution. In both states, lethal injection is the primary method. In NH, hanging can only be used if a lethal injection cannot be given. In Washington, the inmate has to request hanging; otherwise, they get a lethal injection.
As an aside, it seems I was wrong that the federal government only uses lethal injection. That is actually the US military. The federal government uses the "manner [of execution] prescribed by the law of the State in which the sentence is imposed. If the law of the State does not provide for implementation of a sentence of death, the court shall designate another State, the law of which does provide for the implementation of a sentence of death, and the sentence shall be implemented in the latter State in the manner prescribed by such law." 18 USC 3596(a).
So I guess if they got sentenced for treason in NH or WA, they could get hung.
Although this is the legal definition of treason...
Whoever, owing allegiance to the United States, levies war against them or adheres to their enemies, giving them aid and comfort within the United States or elsewhere, is guilty of treason and shall suffer death, or shall be imprisoned not less than five years and fined under this title but not less than $10,000; and shall be incapable of holding any office under the United States.
18 USC 2381
Anyone want to explain to me what the Obamas have done to be guilty of that?