8 USC 12.2.4.1227.4.A. Deportable aliens
http://www4.law.cornell.edu/uscode/html/uscode08/usc_sec_08_00001227----000-.html#a_4_A(A) In general
Any alien who has engaged, is engaged, or at any time after admission engages in—
(i) any activity to violate any law of the United States relating to espionage or sabotage or to violate or evade any law prohibiting the export from the United States of goods, technology, or sensitive information,
(ii) any other criminal activity which endangers public safety or national security, or
(iii) any activity a purpose of which is the opposition to, or the control or overthrow of, the Government of the United States by force, violence, or other unlawful means,
is deportable.
8 USC 12.2.8.1326. Reentry of removed aliens
http://www4.law.cornell.edu/uscode/html/uscode08/usc_sec_08_00001326----000-.html(a) In general
Subject to subsection (b) of this section, any alien who—
(1) has been denied admission, excluded, deported, or removed or has departed the United States while an order of exclusion, deportation, or removal is outstanding, and thereafter
(2) enters, attempts to enter, or is at any time found in, the United States, unless
(A) prior to his reembarkation at a place outside the United States or his application for admission from foreign contiguous territory, the Attorney General has expressly consented to such alien’s reapplying for admission; or
(B) with respect to an alien previously denied admission and removed, unless such alien shall establish that he was not required to obtain such advance consent under this chapter or any prior Act,
shall be fined under title 18, or imprisoned not more than 2 years, or both.
8 USC 12.2. Immigration
http://www4.law.cornell.edu/uscode/html/uscode08/usc_sup_01_8_10_12_20_II.html8 USC 14.1601. Statements of national policy concerning welfare and immigration
http://www4.law.cornell.edu/uscode/html/uscode08/usc_sec_08_00001601----000-.html