Note "the Australian Government is proposing to introduce legislation to the Parliament when it resumes in May" https://www.covidsafe.gov.au/help-topics.html
Look forward to seeing an exposure draft bill asap. #AusLaw
As for what should be in this bill? See: https://twitter.com/political_alert/status/1254229851055296514

See the draft model statute drafted by UK experts: https://twitter.com/lilianedwards/status/1249719259938381826?s=20

This draft model legislation has been cited with approval by UK's Biometrics Commissioner: https://twitter.com/mikarv/status/1254026255588118529

See also the recommendations from the @AdaLovelaceInst as to what should be included in primary legislation re contact tracing apps: https://www.adalovelaceinstitute.org/wp-content/uploads/2020/04/Ada-Lovelace-Institute-Rapid-Evidence-Review-Exit-through-the-App-Store-April-2020-1.pdf (page 12)