A former top aide to two Supreme Court Chief Justices has stirred up legal circles by outlining possible grounds for a court challenge of Ontario’s use of the notwithstanding clause to override a court ruling that struck down a bill cutting Toronto city council by nearly half.

Lawyer Gib van Ert, who was the executive legal officer to Chief Justice Richard Wagner until last month, suggested on his Twitter account that an appeal could be successful by claiming Premier Doug Ford’s move contravenes Canada’s international obligations.

Van Ert’s argument centres on Canada’s obligations under the 1966 UN International Covenance on Civil and Political Rights, which restricts signatory nations from overriding legal and human rights guarantees except when facing dire emergencies that threaten the nation.

The Supreme Court of Canada has said that the Charter should be interpreted according to international human rights treaties to which we are a party. Does this presumption narrow the scope of s 33, the #notwithstandingclause? Thread. [1/14] — Gib van Ert (@gibvanert) September 11, 2018

The Supreme Court of Canada has said “the Charter should be presumed to provide at least as great a level of protection as found in the international human rights documents that Canada has ratified,” van Ert said in his Twitter thread.

Van Ert, who was also executive legal officer to former Supreme Court chief justice Beverley McLachlin, cited a history of federal government and court statements on the notwithstanding clause that Ford and his government have used to force massive changes to the Toronto’s ward system in the middle of a civic election.

In fact as early as 1984, when the Charter was new, Canada told the Human Rights Committee “any resort to section 33 would have to be compatible with Canada’s international obligations” (UN doc. CCPR/C/SR.559 at [28]). [13/14] — Gib van Ert (@gibvanert) September 11, 2018

“So, the argument is there to be made,” van Ert, an expert on international human rights, said in his final tweet on the topic. “Whether a court would accept it, who knows? But if s. 33 isn’t limited in this way, it is probably contrary to international law.”

Toronto Mayor John Tory announced Thursday the city is going to mount a court challenge of the Ontario government’s invocation of the notwithstanding clause after Ontario Superior Court Justice struck down the measure that was throwing the Toronto municipal election into chaos.

“There’s been very little court litigation over that, over the years, but maybe there will be some now,” said Tory, who declined to provide any detailed information about the court challenge.

“I can’t say yet, because we gave instructions to our solicitors and that was all a confidential discussion of course because we don’t want to outline our legal advice and our legal strengths and weaknesses,” Tory said in an interview on CBC’s Power and Politics.

Van Ert’s argument drew attention from prominent University of Ottawa law professor Craig Forcese, among others, who commented positively the same day Tory announced the city’s decision to challenge the Conservative government’s move.

Gib’s thoughts in this thread are the best analysis I’ve seen suggesting there is a legally meaningful fetter on s.33. This could actually fly on the logic of the law as it stands. https://t.co/YbCp03LGzt — Craig Forcese (@cforcese) September 13, 2018

Van Ert, who is now establishing his own firm with offices in Ottawa and Vancouver, also declined to comment beyond his Twitter remarks on Tuesday.