Over the course of three days this week, the prime minister was poked and prodded for a position on Bill 62.

The Quebec law, passed by the provincial legislature on Tuesday, prohibits anyone delivering or receiving public services from covering their face. That again makes an issue of the niqab.

On Wednesday, in the House of Commons, a Bloc MP asked Justin Trudeau to guarantee the federal government would neither challenge the law nor fund a challenge.

"I will continue to ensure that all Canadians are protected by the charter, all while respecting the choices made by lawmakers at all levels," Trudeau said.

On Thursday, in Quebec, Trudeau told reporters "it's not up to the federal government to challenge" Bill 62.

And for that and other comments that suggested deference or timidity, he was chided.

The PM expands his comments during a visit to a paper mill in Alma, Quebec 0:41

On Friday, the prime minister was confronted again. "As a federal government," he told reporters at another stop in Quebec, "we're going to take our responsibilities seriously and look carefully at what the implications [of the bill] are."

For Trudeau, it is now down to how he chooses to exercise those responsibilities.

Trudeau's options for Bill 62

Technically, the federal government might not be able to "challenge" Bill 62 in court.

"The federal government does not have standing to directly challenge a provincial law on the basis of the charter, because governments don't enjoy charter rights," said Carissima Mathen, vice-dean of the faculty of law at the University of Ottawa.

But the Liberals do have options if they want to get involved.

If an individual launches a challenge, the federal government could seek to act as an intervenor and file arguments in the subsequent proceedings. In 2013, for instance, the federal government intervened in a case involving Quebec's Bill 99, which deals with secession.

A re-instated Court Challenges Program could also, conceivably, help fund a challenge.

Alternatively, the federal government could refer the legislation directly to the Supreme Court, asking the high court to review its constitutionality instead of waiting for any legal challenge to reach that level. The federal government could make arguments in those proceedings.

When Pauline Marois's Parti Québécois government proposed its "charter of values" in 2013 — a more expansive attempt to regulate the wearing of religious symbols — the Conservative government of the day seemed ready to get involved.

"If it's determined that a prospective law violates the constitutional protections to freedom of religion to which all Canadians are entitled, we will defend those rights vigorously," Jason Kenney, as multiculturalism minister, said at the time.

The Marois government was defeated before that willingness could be tested.

Trudeau's record on the niqab

While the charter of values was up for debate, Trudeau, as leader of the third party, was quick to denounce it. In 2013, he penned an op-ed for the Globe and Mail on the subject

Later, when Kenney's own move to ban the niqab from citizenship ceremonies was being contested, Trudeau delivered a long and considered speech on the issue. When Kenney's gambit became an election issue, Trudeau's opposition became a mark of his leadership.

But it is perhaps easier to condemn a federal government or a separatist Quebec premier than it is to castigate a federalist Quebec premier. And a prime minister might have to exercise more caution than the leader of a third party.

It is still unclear how or where the law will be applied. And Bill 62 might eventually be struck down — or mocked out of existence — regardless of federal involvement.

People covering their faces waited at bus stops along Parc Avenue in Montreal on Friday to protest Bill 62. (Sudha Krishnan/CBC)

But if Bill 62 is an objectionable piece of legislation, anything less than a full-throated condemnation might seem to fall short.

"I will always stand up for Canadians' rights, I will always stand up for the Charter of Rights and Freedoms. It's what Canadians expect of me," Trudeau said on Friday.

"As I've said a number of times, as well, I don't think it should be the government's business to tell a woman what she should or shouldn't be wearing."

Depending on how events proceed in Quebec, he might be called on to say that again and again, maybe louder or somehow more forcefully.

Regardless, he could also have the Justice Department's lawyers get involved at some point.