Every now and then the High Court overturns a past decision, most notably in the 1920 Engineers case where the court rejected some decisions concerning constitutional interpretation made during the previous decade or so.

It’s possible, just possible, that future justices may reverse the court’s decision — sitting as the Court of Disputed Returns — in the recent citizenship case. But this would be many years away in view of the seven-to-zip decision concerning the right of senators Matt Canavan, Scott Ludlam, Larissa Waters, Malcolm Roberts, Fiona Nash and Nick Xenophon along with (former) New England member Barnaby Joyce to sit in the federal parliament. All except Canavan and Xenophon were ruled ineligible. In these two cases the court had difficulty in establishing the senators’ precise citizenship status.

Attorney-General George Brandis has described the decision as “brutalist” with respect to its strict interpretation of section 44 of the Constitution. Others have referred to the decision of Chief Justice Susan Kiefel and her colleagues by the term “black-letter law”. The citizenship case is certainly an example of black-letter law. Sure, the court followed the majority decision in the 1992 case of Sykes v Cleary and Others — in which justice William Deane dissented. In the recent case, the court specifically distanced itself from Deane’s judgment.

In doing so, justices Kiefel, Virginia Bell, Stephen Gageler, Patrick Keane, Geoffrey Nettle, Michelle Gordon and James Edelman stated that “the approach to construction urged by the amicus (friend of the court) and on behalf of Mr (Tony) Windsor gives s. 44(i) its textual meaning” subject to one qualification.

The qualification referred turns on the “constitutional imperative … that an Australian citizen not be prevented by foreign law from participation in representative government where it can be demonstrated that the person has taken all steps that are reasonably required by foreign law to renounce his or her citizenship”.

Otherwise, the court was into the darkest of black-letter law in this case. For example, early in the judgment, the following statement is made: “There is evident force in the submission of the amicus that s. 44(i) consists of only two limbs: the verb ‘is’ is used in s. 44(i) only twice, and there is a comma followed by the disjunctive ‘or’ at the end of the first limb but not within the second limb.”

Now, when judges talk about the placement of a comma and the number of occasions a verb is used in a section that came into effect in 1901, that’s black-letter law. Yet it would be inaccurate to maintain that Kiefel presides over a court packed to the brim with brutalist judges.

As the court’s recent decision in Robert James Brown v The State of Tasmania demonstrates, all is not brutalist black letter in the Kiefel court’s judgments. In Brown’s case, six out of seven judges — Edelman dissenting — struck down some sections of the Tasmanian Workplaces (Protection from Protesters) Act because they “impermissibly burden” the “implied freedom of political communication contrary to the commonwealth Constitution”.

Around two decades ago, I was present when a young Australian asked a High Court judge how to find an implied freedom by reading the Constitution. His honour’s response was along the following lines: “Well, you can’t; it’s not there in words.”

Brown v Tasmania is an important case covering the right to demonstrate. Bob Brown, the former Greens senator, was arrested and charged after protesting against logging. The charge was not proceeded with but Brown challenged the validity of certain provisions in the legislation.

Brown v Tasmania is a complicated case and it remains to be seen how the court’s decision will affect the right to protest. But we do know that Brown welcomed the decision as putting “a brake on corporations” since he believes it will facilitate the right of protesters to disrupt business activity to protect forests.

In any event, the majority of the court found an implied freedom of political communication in the Constitution. In his dissenting judgment, Edelman stated that “however high the value that one puts upon a freedom of political communication, the constitutional area of ‘immunity from legal control’ does not extend to persons whose conduct is independently unlawful”.

The six judges who in Brown’s case found an implied freedom of political communication in the Constitution rejected Deane’s judgment in Sykes v Cleary. Deane had held that section 44(i) of the Constitution should “be constructed as impliedly containing a … mental element with the result that it applies only to cases where the relevant status, rights or privileges have been sought, accepted, asserted or acquiesced in by the person concerned”.

In other words, Deane held the view that, due to an implied right, citizenship of a foreign country could not be acquired merely by descent. However, this is not the law of Australia as interpreted by the High Court.

In view of the historical difficulty in attaining a majority of Australians in a majority of states to support amending the Constitution, there is no option but to adjust to the law as interpreted by the court. This may lead to a situation where, unbeknown to a politician, a foreign nation changes its citizenship rules and makes an Australian a citizen by descent and hence unable to be a member or senator in the federal parliament.

The citizenship case is yet another disruption in our midst. But it has not been brought about by a High Court that is committed to black-letter law in all its decisions.