The conference was being organised to mark centenary the of the Habitual Offenders Act, which came into force in 1914.
Justice R Subbiah of Madurai bench directed police to grant permission to the petitioner for the conference.
Some 16 persons were killed in the agitation against the Act at Perumangamanallur in 1920.
Vice President of the association R Tirupathi contended in his petition that he was allowed to hold street corner meetings in January this year. But police were refusing to permit state level conference and sought the intervention of the court and direct police to grant permission.