If you're applying for asylum in the U.S., you might have to wait until you're granted asylum before you qualify for a work permit, or navigate some complicated immigration rules.
When a lawful permanent resident (green card holder) is arrested by law enforcement, the consequences may include revocation of the immigrant visa and deportation, even without a criminal conviction.
Overview of how basic ineligibility, criminal charges and other grounds of inadmissibility, or difficulties in the application process prevent some applicants from success.