Former High Court justice Bill Gummow has questioned Scott Morrison’s decision to take on extra ministerial portfolios, saying the “clandestine appointments” were invalid because of the secrecy involved.

Mr Gummow, who served on the court from 1995-2012, said Solicitor-General Stephen Donaghue, QC, was wrong to advise the incoming government that the extra jobs for the former PM complied with section 64 of the Constitution.