The Supreme Court of Canada heard arguments Thursday in the case of a woman who wants to testify in court while wearing a niqab, in a legal matter that pits religious rights against the right of defendants.

The woman, identified only as N.S., wants to wear her niqab — a veil-type cloth that covers all of her face, except her eyes —during testimony against two male relatives in a sexual assault case in Ontario. The woman is the complainant in the case, and made the request to wear her niqab based on her Muslim beliefs.

The defendants, however, say they should be able to see the facial expressions of N.S. for the purpose of cross-examination.

A preliminary inquiry judge ordered that she remove her niqab before testifying, but an Ontario Superior Court judge later quashed that order.

The Ontario Court of Appeal subsequently overturned the Superior Court's order, set up a legal test for determining if the woman can wear her niqab, and sent the matter back to the preliminary hearing judge.

The woman appealed that decision to the country's top court in Ottawa, contending her right to wear the niqab is protected by the Charter of Rights and Freedoms. She wants the Supreme Court to send the matter back to the preliminary inquiry with an order that she be allowed to wear the niqab at the hearing and any trial that might follow.

Demeanour 'not the be all and end all'

Her lawyer says certain institutions, including courts, need to take people as they are without making them pay a price for sincerely held beliefs.

"There are lots of other ways to assess demeanour – body language and voice for example. But also demeanour is not the be all and end all. There are many other ways through cross-examination, examining the reliability of a witness's evidence …and a niqab does not interfere with that," said David Butt.

But no one should presume a woman wears a niqab for religious reasons, says the lawyer for the Canadian Muslim Congress. "There are a number of reasons that a woman could wear a niqab, they could be cultural, they could be political, they could be familial and if there's no connection to religious, it doesn't deserve constitutional protection," said Tyler Hodgson.

A lawyer for one of the accused argued he needs to physically see the witness in order to judge her demeanour and credibility.

Douglas Usher said a smirk or furrowed brow often says more than the spoken word.

But people can also judge demeanour from eye contact, voice and movements, said Julia Williams, who is with the Canadian Council on American-Islamic Relations.

Williams said banning the niqab in court could lead to fewer Muslim women reporting crime or agreeing to testify.

"If there's some sort of judgment that says upfront that women in niqab aren't allowed in the courtroom, can't testify, [then] women who have important claims like N.S., about alleged sexual assault, might not come forward at all and that would be a huge disservice to justice in Canada," Williams said.

"She's going to be physically present, emotionally present, intellectually present ... what will make her not present are rules that say you cannot come here and testify with your niqab on. That will truly make her invisible."

A ruling in her favour, however, could lead to distasteful requests like requesting a male judge or a judge of a certain religion, says Frank Addario, a lawyer representing the Criminal Lawyers' Association.

The Supreme Court typically takes several months to make its rulings.

With files from Alison Crawford