In a 5-3 decision authored by Justice Kennedy, the Supreme Court struck down most of the main provisions of an Arizona law targeting illegal immigration. The law, known as the “Support Our Law Enforcement and Safe Neighborhoods Act” or “S.B. 1070,” codified Arizona’s policy of “attrition through enforcement.” This policy presumes that undocumented individuals will leave the United States in response to unfavorable or hostile laws. Four provisions of the law were at issue in this case:

*Section 3, criminalizing the “willful failure to complete or carry an alien registration document …”...