Grounds of Deportability
Here's a brief summary of the types of personal characteristics or history that may make someone deportable.
Having gained legal status by committing marriage fraud
Being a terrorist
Having been convicted of certain crimes
Having helped smuggle aliens into the U.S.
Having not deserved an earlier grant of legal status, because the person was inadmissible at the time
Having failed to timely notify U.S. Citizenship and Immigration Services (USCIS) of one's changes of address
Having falsely claimed to be a U.S. citizen in order to gain a benefit from the government