Article II, Section 1, of the U.S. Constitution (http://www.archives.gov/exhibits/charters/constitution_transcript.html) states:
No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any Person be eligible to that Office who shall not have attained to the Age of thirty five Years, and been fourteen Years a Resident within the United States.
Philip J. Berg, an attorney, claims that Barrack Obama is not a natural born Citizen of the United States, and therefore is ineligible to be President. Mr. Berg has filled a lawsuit in Federal District Court to block Obama from becoming president.
Links: