Defence Minister Senator David Johnston, in his Parliament House office.

Defence Minister Senator David Johnston, in his Parliament House office. Photo: Alex Ellinghausen

Since the election of the Abbott government in September, Senator David Johnston, the Minister for Defence, has not exactly captured the public eye.

One doubts whether one Australian in a hundred, or even perhaps a thousand, would recognise him in the street. But his chances of being noticed have probably risen somewhat as a result of the remarkable tantrum he produced when talking to the press on February 7.

The trigger for his performance was reporting by the ABC of claims from an asylum seeker, Yousif Ibrahim Fasher, about the circumstances in which several other asylum seekers were burned on the hands. Johnston did not hold back.

Describing the claims as ''hearsay, innuendo, and rumour'', he claimed that ''the good men and women of the navy'' had been ''maliciously maligned by the ABC''. He added that ''I have discussed this matter with senior command'', and went on that ''they have assured me that there is no substance to these allegations''.

He then offered a threat: ''If ever there was an event that justified a detailed inquiry, some reform, and investigation into the ABC, this is it''. To those with a sense of history, memories of Richard Nixon's attacks on The Washington Post during the Watergate scandal would fairly quickly come to mind.

Fuelled by a further detailed interview with Fasher that had appeared in the Fairfax papers that very morning, the journalists who were witnesses to this spectacle hit back hard. Pressed on detail, the minister sought to retreat. ''Please, please,'' he said, ''I'm not aware of operational matters, you need to put that to Border Protection Command.''

This prompted the scornful comment ''so you're not aware of operations involving your own personnel as the Minister of Defence?'' Another journalist asked: ''Well can you explain what the circumstances of the burnt hands were?'' The minister's reply was telling, although perhaps not in the way he thought: ''No I can't, they are on-water matters that are not my responsibility because it is a civil public policy matter.''

Johnston is a figure of little note, and the ABC leadership is unlikely to be too fussed about his hysterics. Nonetheless, the wider episode highlights very interesting points about the nature of evidence that merit further attention.

At the outset, it is quite wrong to describe Fasher's testimony as ''hearsay, innuendo, and rumour''. On the contrary, he has supplied eyewitness claims.

They would be hearsay only if he were quoting claims made by someone else.

Furthermore, the claims made by Fasher in his Fairfax interview were not about ''the men and women of the navy'', but about a very small number of sailors who happened to be on a particular boat at a particular time.

Several other lines of attack have been used by the government. One is that the claims made by Fasher are ''unsubstantiated''. This is a curious claim to make, because the testimony of one credible witness can be quite enough to underpin firm conclusions in both historical analysis and legal cases.

Another line of attack has been to the effect that the testimony of Fasher cannot be accepted because it is in his interest to make such a claim. The logic of this is not obvious, since his testimony is likely to put him close to the top of the government's list of enemies. But more seriously, it misses another point. If indeed a small number of rogue sailors behaved as Fasher claimed, they would have at least as strong an interest in putting out blanket denials as Fasher would have in putting out a false claim.

This leads us to the question of how people such as Prime Minister Tony Abbott and Johnston can offer such firm opinions about events on a boat somewhere between Indonesia and Australia. This, interestingly, is where hearsay enters the story.

It is plain that our offended political leaders were nowhere near the theatre of operations. But nor were the ''senior command'' on whose words they now rely.

The Chief of the Defence Force and the Chief of Navy, let alone the frenzied columnists of the

Murdoch press, are in no position to offer eyewitness testimony. If there is comprehensive, continuous film footage of what went on at all times in the passageway in which Fasher alleges that the events took place, it would be very easy for the navy hierarchy to make that available and put the story to rest.

The fact that they have not done so strongly suggests that there is no such footage. In that case, the government's position must be based on denials fed up the chain of command from those who might have been involved, combined with faith in the navy as an institution.

So what actually happened on the fishing boat? At this point I am unsure, but as a citizen I would like to know, and only an independent investigation is likely to provide a credible answer. I am quite sure that there was and is no naval policy to inflict burns on asylum seekers, but this has never really been the issue in point. Nevertheless, past experience should teach us a few sobering lessons.

First, from the Voyager disaster to children overboard, senior echelons of the navy have had an unhappy history of not sharing the full story with the public when things go wrong.

Second, as the hideous case of HMAS Success makes clear, large organisations can easily have rotten apples in their midst - something which, in the event that Fasher's testimony were to be found accurate, would provide the most plausible immediate explanation of the events.

The navy has many wonderful people in it, but it is naive and foolish to believe that it does not also have its share of bullies and bigots, especially in the lower ranks. But, third, we should also note that the sailors involved in Operation Sovereign Borders have gone to sea with a great deal of poisonous political rhetoric ringing in their ears, demonising and dehumanising those seeking to flee from persecution. Is it really likely that this would have had no effect on any of them?

Professor William Maley is director of the Asia-Pacific college of diplomacy at the Australian National University.