Permanent residents who have criminal records should exercise caution.
Think before making any trip abroad, seeking new immigration benefits, or applying for citizenship. You may be denied admission if these “inadmissibility” grounds apply if you:
(1) have abandoned or relinquished your permanent resident status,
(2) have been absent from the United States for a continuous period in excess of 180 days,
(3) have engaged in illegal activity after their departure from the U.S.,
(4) have departed from the U.S. while in removal or extradition proceedings,
(5) have committed a criminal or related offense (including “crimes of moral turpitude”, drug trafficking, or prostitution),
(6) are attempting to enter at a place other than a designated port of entry or have not been admitted to the U.S. after inspection and authorization by an immigration officer.
Some relatively minor crimes may be grounds for inadmissibility. These might not come to the attention of immigration authorities until you return to the U.S. after traveling abroad. At that time you may be denied entry.
Many of the grounds of inadmissibility can be waived in individual cases. For example, INA § 212(d)(3) allows the Secretary for Homeland Security to waive any of the grounds, except for a few security-related provisions, for nonimmigrants applying for a visa or seeking admission. Waivers for permanent residents are more limited.