Senate estimates hearings have recently taken place covering, as they always do, a wide range of matters. These included the proposed Minerals Resource Rent Tax. At the hearings, Treasury officials indicated that they had previously received advice from the Commonwealth Solicitor General in relation to the then-proposed Resource Super Profits Tax (originally announced on 2 May, 2010) that "… there is a risk that a court would find that the law discriminated between States for the purposes of s 51(ii) [of the Constitution], and was therefore outside the scope of the taxation power". Treasury noted that the advice related to a proposal that is no longer government policy.

However, Treasury said it was currently working out the details of the proposed new Minerals Resource Rent Tax, and would, as is standard practice, "no doubt … seek advice from AGS as to a range of matters including constitutionality" and would, in formulating that detail, take into account the advice it had previously received.

Source: Senate Economics Legislation Committee Hansard, 21 October 2010 [proof copy, pp E62, E63, E76]