South Australian law does not cover this ground of discrimination, but Commonwealth laws applying in South Australia cover discrimination on this ground in the area of work only.
In Commonwealth law, it is unlawful to treat a person unfavourably in their work because of their political opinion, including trade union activities. This includes refusing to hire them, hiring them on less favourable terms, denying them access to any benefits that go with the job, dismissing them or subjecting them to other adverse treatment. Commonwealth law does not cover this type of discrimination in any other area apart from the workplace.
The Fair Work Commission can accept claims about discrimination in work on the ground of political opinion, under the Fair Work Act 2009 (Cth) s 351. See the Employment chapter of the handbook on protected workplace rights: General Protections.