Any investigation of the Nauru leak to The Guardian could trigger the first use of the Journalist Information Warrant scheme, whereby two former judges appointed by the PM (“public interest advocates”) will decide whether it’s in the public interest to allow the Australian Federal Police to access the metadata of the Guardian Australia journalists involved with the story, says the journalism union. The Media, Arts and Entertainment Alliance has previously raised concerns that Supreme Court justices Kevin Duggan and John Muir, appointed to the panel in January to argue against secret warrant applications by police, have no media experience.

It’s not clear any such investigation is going on, though MEAA says one would expect it from past experience. Paul Farrell, the journalist who came into possession of the files some months ago, has previously had his sources investigated by the AFP. The last time it happened was before the amendments requiring extra hurdles for accessing journalists’ metadata were passed by Parliament — forced through by Labor as the cost of its support for mandatory metadata retention.