32 CFR § 147.3 - Guideline A - Allegiance to the United States.
(a) The concern. An individual must be of unquestioned allegiance to the United States. The willingness to safeguard classified information is in doubt if there is any reason to suspect an individual's allegiance to the Untied States.
(b) Conditions that could raise a security concern and may be disqualifying include: (1) Involvement in any act of sabotage, espionage, treason, terrorism, sedition, or other act whose aim is to overthrow the Government of the United States or alter the form of government by unconstitutional means;
(2) Association or sympathy with persons who are attempting to commit, or who are committing, any of the above acts;
(3) Association or sympathy with persons or organizations that advocate the overthrow of the United States Government, or any state or subdivision, by force or violence or by other unconstitutional means;
(4) Involvement in activities which unlawfully advocate or practice the commission of acts of force or violence to prevent others from exercising their rights under the Constitution or laws of the United States or of any state.
(2) The individual's involvement was only with the lawful or humanitarian aspects of such an organization;
(3) Involvement in the above activities occurred for only a short period of time and was attributable to curiosity or academic interest;
(4) The person has had no recent involvement or association with such activities.