Southern is one of the founder members of Jersey's only political party, inaugurated to the States of Jersey on 4 July 2014, "Reform Jersey". Reform Jersey was originally set up in 2012 to campaign for reforms to Jersey's democratic system. In 2014, following the election to the States of Jersey of Reform Jersey's chairman Sam Mezec, and founding member Nick Le Cornu, the group decided to reconstitute as a political party, in order to campaign for wider principles of social and economic justice.