A Permanent Resident Card, commonly known as a Green Card, is evidence of your status as a lawful permanent resident with a right to live and work permanently in the United States. It also is evidence of your registration in accordance with United States immigration laws.
Section 264 of the Immigration and Nationality Act provides that, "Every alien in the United States shall be issued a certificate of alien registration or an alien registration receipt card in such form and manner and at such time as shall be prescribed under regulations." It also states, "Every alien, eighteen years of age and over, shall at all times carry with him and have in his personal possession any certificate of alien registration or alien registration receipt card issued to him. Any alien who fails to comply with [these] provisions shall be guilty of a misdemeanor."