It's from the 1952 Immigration and Nationality Act, here's the relevant portion: https://www.law.cornell.edu/uscode/text/8/1357#a_3 https://www.law.cornell.edu/

It's from the 1952 Immigration and Nationality Act, here's the relevant portion: https://www.law.cornell.edu/uscode/text/8/1357#a_3 https://www.law.cornell.edu/uscode/text/8/1357#a_3 . It should be noted the constitutionality of that section has been upheld by the Supreme Court, for instance in https://en.wikipedia.org/wiki/United_States_v._Martinez-Fuerte https://en.wikipedia.org/wiki/United_States_v._Martinez-Fuer... .