There is an expectation in Australia that once the result of the same-sex marriage postal vote is announced on 15 November the matter will be resolved once and for all. According to opinion polls a Yes vote looks likely, clearing the way for amendments to the Marriage Act. But there’s a twist in this long-running, angry issue (on 21 September a man head-butted former prime minister Tony Abbott as he campaigned for a No vote). Opposition leader Bill Shorten seeks to define marriage as ‘a union between two people’ meaning that all are eligible: heterosexuals, homosexuals and people of any other gender or sexuality. This could be immensely complicated.