Attorney-General George Brandis has sought to defuse the scandal over the Australian Tax Office’s successful overturning of a Western Australian law by saying he was unaware of any agreement with the Barnett government, and he knew nothing of what then-treasurer Joe Hockey had negotiated with his WA counterpart.

Last week The West Australian newspaper revealed the Australian Tax Office’s successful attempt to thwart Western Australian legislation relating to the collapse of the Bell group of companies — which would have cost the ATO $300 million in tax revenue — might have breached a secret deal between the Commonwealth and the WA government that the former would not challenge the WA legislation. However, Brandis said, correspondence between Hockey and Nahan did not show any evidence of a deal, and neither he nor Assistant Treasurer Kelly O’Dwyer were aware of one.

Hockey’s response to Nahan makes no reference to any deal not to challenge the WA legislation, but Nahan’s letter refers explicitly to the hope that the Commonwealth would not intervene, and Hockey does not correct him in his response.

[Why is Brandis in hot water this time?]

Brandis twice left open the possibility that Hockey and Nahan might have reached a deal verbally. “If WA ministers considered their dealings with Mr Hockey to constitute some form of agreement, I could only observe that the only written record of those dealings, the exchange of letters between Dr Nahan and Mr Hockey of April 2015, do not, in my view, constitute or evidence such an agreement. In any event, whatever may have been discussed between Mr Hockey and Dr Nahan, neither I nor Ms O’Dwyer was aware of it at the time.”

Brandis’ response is the second time in recent weeks that, under pressure, he has professed to be oblivious to major issues within the government despite being Attorney-General and a senior member of cabinet. Earlier this month, Brandis claimed he had no interest in or knowledge of the issue of the eligibility of former senator Bob Day, despite the issue being considered within government since 2015.

Nor does Brandis’ statement address the question of why Brandis did not tell Malcolm Turnbull about the issue at some point after the Attorney-General claims he learnt of it in early April. The amount of money at stake, whether there was a deal or not, was $300 million, and it is remarkable that the matter was not the subject of correspondence to the Prime Minister at the very least, or a cabinet discussion — and all the more so given the Barnett government is a Coalition government.

Instead, it is Joe Hockey — now safely out of the political game as ambassador in Washington DC — who gets to wear the suspicion of a dodgy deal to do taxpayers out of hundreds of millions of dollars to help a friendly government.