Nevertheless, in the past two years the Secret Service has arrested more than a dozen Americans for posing credible threats to the president. Because of concerns about his safety, candidate Obama received Secret Service protection earlier than any other presidential hopeful in US history. The Secret Service doesn't publicize most threats, fearing that they could inspire copycat attempts.
The most famous Obama assassination plot involved two neo-Nazi skinheads in Tennessee, who were accused in late 2008 of planning to shoot 88 black people, behead another 14, and then kill Obama. Both men pleaded guilty this year to charges of conspiring to kill Obama.
According to the law, "Whoever knowingly and willfully deposits for conveyance in the mail or for a delivery from any post office or by any letter carrier any letter, paper, writing, print, missive, or document containing any threat to take the life of, to kidnap, or to inflict bodily harm upon the President of the United States ... shall be fined under this title or imprisoned not more than five years, or both."
Vermont comedian Chris King was arrested Oct. 8 for tweeting: "I am dying inside. And I am plainly stating to you that I am going to kill the president.” Such "death tweets" on the social media network Twitter have figured in several high-profile threat arrests.