Sunday Legislation Under Constantine
No historian thinks of denying that Sunday legislation began in 321 A.D., under Constantine; that his first law was pagan, purely, in form, fact, and essence; that it represented the union of church and state after the pagan model. This legislation and the fixing of "Easter" by civil law on Sunday, rather than on the fourteenth day of the month, according to the paschal law of the Jews, completed the civil and political enthronement of Sunday in place of the Sabbath.—A. H. Lewis, in "Swift Decadence of Sunday; What Next?"