One of his important findings is that the principles of responsible government are "fundamentally compromised" when the Parliament and the public are not informed of the appointment of ministers, as happened in these cases. This is because ministers are meant to be accountable to Parliament, and through it the electorate, for their actions and inactions.

A second, material observation is that the concept of responsible government is a "central feature of the Australian constitution system" and the constitution "is permeated through and through with the spirit of ... the institution of responsible government".

A crude but accurate paraphrase is that Morrison's secret ministries trashed the system of responsible government and undermined the constitution. It is thus perplexing that Dr Donoghue nevertheless found that the ministerial appointments were constitutionally sound and otherwise lawful.

That finding rests on the principle that in appointing ministers "there is no doubt that the Governor-General is bound to follow the prime minister's advice".

We know that the Governor-General has reserve powers, not all of which have been specified, that can be exercised contrary to the prime minister's advice. But the Solicitor-General states none of these is relevant to appointing ministers (other than the prime minister).

It might be true that this convention or rule holds in all circumstances, as the Solicitor-General infers, but that would be more than unfortunate.

If Australia is unlucky enough to have a Prime Minister who nominates a minister for improper reasons, say, in exchange for personal financial benefit, would a knowing or informed Governor-General be bound to follow that advice? And if that is the exception that disproves the rule, are there others? If you examine the behaviour of president Donald Trump in the United States, such outrageous possibilities in Australia are not fanciful.

The Solicitor-General seems to offer some hope where he notes that there can be a "constitutional implication" in Governor-General actions where a response is necessary for the preservation of the integrity of the constitution.

But Dr Donoghue denies that such an implication exists in this matter. He safely opts for the status quo, to maintain a sparse constitution, governed by convention and practice, which can accommodate change, in preference to finding there is an implied constitutional requirement that ministerial appointments be notified to Parliament.

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Another, lesser result of the Solicitor-General's advice is that he protects the Commonwealth in litigation on Mr Morrison's decision to deny an extension to Advent Energy's exploration licence for coastal areas off NSW. Had Dr Donoghue advised that Mr Morrison's appointment as resources minister was invalid, that exploration decision would also be invalid.

Not all constitutional lawyers need be so conservative, especially when that allows the integrity of the constitution to be compromised. After all, it is inconceivable that those drafting the constitution would have knowingly allowed the appointment of secret ministers.

But the Solicitor-General, the second law officer of the Commonwealth, is not just a constitutional lawyer. And though the High Court and solicitors-general have often differed on legal matters, the government has little option but to accept Dr Donoghue's opinion and develop statutory options to prevent the future appointment of secret ministers.