U.S. District Judge Murray Snow also said in his decision Friday that being in the United States illegally is not grounds for arrest.
Antonio Bustamente of Los Abogados, the Arizona Hispanic Bar Association, called Snow's ruling "monumentally important," The Arizona Republic reported. Bustamente appeared with other leaders at a news conference Monday at the El Portal restaurant in Phoenix.
Mary Rose Wilcox, a county supervisor who owns El Portal with her husband, said she plans to request an executive session of the board to discuss federal aid Arizona may lose because of Arpaio's actions.
"If Sheriff Arpaio doesn't change, he must step down," Wilcox said. "We will not stand for racial profiling."
Arpaio, 78, a former agent with the U.S. Drug Enforcement Administration, is now in his fifth term as sheriff. He has become nationally known for his get-tough stance on illegal immigrants.