The showdown over Canada's ban on face-coverings during citizenship ceremonies takes center stage in an Ottawa courtroom tomorrow, for a case that has reignited a national debate about multiculturalism and religious freedom in the country.

Last February, the Federal Court of Canada sided with Zunera Ishaq, a Pakistani Muslim woman who sued Canada's immigration ministry over a policy that requires new Canadians remove their face-covering veils — also known as a niqab — while taking their oath of citizenship. The 29-year-old says the niqab ban violates her religious belief that her face and hair must remain covered in the presence of men.

In its ruling, the court deemed the ban "unlawful" — a decision that was met with swift condemnation from the Conservative government. And now, lawyers for Citizenship and Immigration Canada will fight to have its ban upheld by the Court of Appeal.

Prime Minister Stephen Harper has already said that covering one's face while taking the oath required to become a Canadian citizen is "not how we do things here."

"It is offensive that someone would hide their identity at the very moment where they are committing to join the Canadian family," he said earlier this year.

In its factum filed with the court, government lawyers defend the niqab ban, writing that the ministry's guidelines for citizenship ceremonies protect Canada's multicultural values.

The factum lists a number of situations in which it says Ishaq, who has been a permanent resident in Canada since 2008, has lifted her veil in public, including to have her driver's license and health card photo taken, as well as for her citizenship interview and airport screenings. It adds that Ishaq has refused their offer to conduct the oath in a section of the room where she would "not generally be seen by other participants during the very brief period of time when the oath was being recited."

But this does not ensure that she would be lifting her veil in private, away from men.

Immigration Minister Chris Alexander told VICE News this spring that if someone wants to become a Canadian, they have to be seen and heard taking the oath. "When you become a citizen, you don't get to dictate the rules. The rules apply equally to everyone...You don't get to come to Canada and decide the rules don't apply to you," he said.

In an op-ed Ishaq wrote for the Toronto Star in March, she says "I have taken my niqab off for security and identity reasons in every case where that's been required of me," such as taking a driver's license photo or going through airport security.

"I will take my niqab off again before the oath ceremony without protest so I can be properly identified. I will not take my niqab off at that same ceremony for the sole reason that someone else doesn't like it, even if that person happens to be Stephen Harper," she wrote.

Ishaq has also found a strong ally in the government of Ontario, which filed its own factum supporting her position to the court of appeal last week. It argues that requiring a Muslim woman to take off her niqab in order for her to take her citizenship oath "fails to respect and accommodate the diversity of religious beliefs and sociocultural backgrounds of Canadians."

Last week, it was revealed that another Muslim woman has also been fighting the government's niqab policy. Maiia Mykolayivna Zaafrane, of Montreal, filed a complaint to the Canadian Human Rights Commission in April 2014 against Citizenship and Immigration Canada, alleging that its niqab ban was discriminatory and violates the Canadian Human Rights Act. If the commission's tribunal agrees with her, she could receive compensation.

In June, the day the House of Commons broke for summer break, Canada's federal minister of state for multiculturalism tabled new legislation that would require someone to uncover their face when taking the oath of Canadian citizenship.

A poll conducted in March found that most Canadians agree with the Conservatives that women should not wear their niqabs while taking their citizenship oaths.

Follow Rachel Browne on Twitter: @rp_browne