A Canadian newspaper has reported that an Ontario Court judge appeared in a courtroom the day after the US election, wearing a "Make America Great Again" baseball hat - the campaign hat for President-elect Donald Trump.

The Globe and Mail says Justice Bernd Zabel wore the hat into the courtroom and addressed the lawyers, police offices and defendants in attendance.

"The incident has prompted an outcry from legal observers who say Justice Zabel’s political display undermines the public’s confidence in judicial impartiality. And they are particularly upset because Mr. Trump has made disparaging remarks about women and minorities," the newspaper says.

“The clerk said ‘all rise’ and the door opens and Justice Zabel comes out," according to the newspaper quoting an unidentified source..

"He is in a black silk robe with the crimson sash and the white tie. He has a poppy on his lapel. And he is wearing a scarlet-coloured baseball cap that says Make America Great Again. And we all stand because we are supposed to stand when the judge comes in and he looks at everyone and said he was wearing the hat ‘because last night was an historic occasion."

“He took the hat off and put it on the bench so everybody could look while he continued his court business. He didn’t put it away. It was sitting on the bench.” Mr. Zabel then came back with the hat after morning break, the source said.

The incident has caused a furore in Canada, with Osgood Hall law professor Gus Van Harten lodging a formal complaint with the Ontario Judicial Council. However, another law professor, Troy Riddell from the University of Guelph, says he would be surprised if the incident resulted in Justice Zabel's removal from the bench.

"We do not know if Justice Zabel supported Trump's anti-establishment narrative, or his policies on trade or ISIS, or the darker undertones of Trump. This differs, for example, from judges who have directly made inappropriate comments about women or minorities," he has told the Hamilton Spectator.