TORONTO - A court battle in which a woman is fighting for the right to wear a religious veil while testifying had lawyers arguing Friday whether the eyes and a voice are enough to assess the credibility of a witness on the stand.

The woman, an alleged sexual assault victim, wears the niqab - a Muslim veil which covers the entire face except for the eyes.

While lawyers for the men accused of assaulting the woman argue seeing her face as she testifies is a fundamental right, the woman's legal counsel says the courts routinely observe and protect religious rights.

The case, unfolding in Ontario Superior Court, is believed to be the first of its kind in Canada.

The face is needed to assess a witness' demeanour and credibility, said lawyer Jack Pinkofsky, who represents the defendants in the sexual assault case.

"You can't separate the spoken word from the face," said Pinkofsky, who argued even the twitch of an eyebrow forms part of the evidence a judge or jury can use to convict.

"The face of justice cannot be faceless."

Wearing a veil wouldn't harm the court's ability to assess the woman's demeanour because the face is only part of the equation, her lawyers said.

Tone of voice and body language are important and the eyes complete the picture, they said.

"You can read everything in the eyes. The eyes are the window to the soul," David Butt, the alleged victim's lawyer, said outside of court.

Prabhu Rajan, a lawyer for the Ontario Human Rights Commission, called the question of wearing a niqab a red herring because of the other ways defence lawyers could assess the woman's credibility as a witness.

"I question the need to see her face at all," he told the court.

To force the removal of the veil, Rajan said, would be a "substantial" interference with her religious beliefs.

"The courts should not be the arbiter of religious dogma," he said.

When it comes to dealing with religious beliefs, the Supreme Court has a "hands off" policy, said Butt, noting the high court's decisions frequently accommodate religious practices.

In 2006, the Supreme Court ruled unanimously that a Quebec school board was wrong to tell a 12-year-old Sikh boy he could not wear his ceremonial dagger in the classroom. The court said the school board infringed on the boy's guarantees of religious freedom.

The hearing continues April 3.