The immunity of certain American Indians born in Canada from exclusion and deportation rules is derived from the Jay Treaty of 1794 with Great Britain and was reaffirmed in the Treaty of Ghent at the conclusion of the War of 1812. See INA 289; 8 C.F.R. 289. The beneficiary must be 50% or more of the blood of the American Indian race and if s/he qualifies, cannot be deported or excluded from the United States for any reason. The language of INA 289 (based on the Jay Treaty) is as follows: "Nothing in this title shall be construed to affect the right of American Indians born in Canada to pass the borders of the United States, but such right shall extend only to persons who possess at least 50 per centum of blood of the American Indian race." Practically speaking, the U.S. government looks at tribal membership cards.  http://www.ptla.org/ptlasite/wabanaki/jay.htm