The State of Aurora requires licenses of persons "who are engaged in the trade of barbering." It will grant such licenses only to those who are graduates of barber schools located in Aurora, who have resided in the state for two years, and who are citizens of the United States. The requirement that candidates for licenses must be citizens is
constitutional as an effort to ensure that barbers speak English adequately. constitutional as an exercise of the state police power. unconstitutional as a bill of attainder. unconstitutional as a denial of equal protection