In May 1970, the Revolutionary Intellectuals Seminar was held to bring intellectuals in line with the revolution, while that year's Legislative Review and Amendment united secular and religious law codes, introducing sharia into the legal system. Ruling by decree, the RCC maintained the monarchy's ban on political parties, in May 1970 banned trade unions, and in 1972 outlawed workers' strikes and suspended newspapers. In September 1971, Gaddafi resigned, claiming to be dissatisfied with the pace of reform, but returned to his position within a month. In February 1973, he resigned again, once more returning the following month.