OTTAWA - A coalition representing a broad range of interests has filed a new court challenge to the federal government's decision to scrap the mandatory, long-form census.

The Canadian Council on Social Development is spearheading the case in Federal Court to defend what it calls "the equal right of all Canadians to be counted."

The Conservative government announced last spring it would do away with the mandatory, long-form census, claiming it was an unjustifiable imposition on privacy.

Its decision to replace it with a voluntary questionnaire has been widely panned by experts and others who say an optional survey would be inaccurate and unreliable.

The 90-year-old council says it's "responding to the overwhelming and very real concerns about the consequences of this catastrophic decision."

Papers were filed with the court on Thursday and no dates have been set for hearings.

The council is joined in its challenge by a dozen social, community and legal organizations.

"Just over 100 days have passed since the Harper government launched its assault on Canada's fundamental data source with a sneak attack on the long-form census," said a group statement.

"The most reliable, comprehensive source of information -- relied on as a tool to respond to the needs and priorities of every Canadian -- wiped out, against the advice of experts across the country and abroad, on a political whim."

The council says Canadians' response to the decision has been unequivocal: "Why would the government shut down Canada's navigation system?"

Despite an outcry from more than 370 organizations and "tens of thousands of Canadians," the government refuses to reconsider its decision.

'Listen, every drug that you take, every life-saving procedure, is based on voluntary information so when our pharmaceutical industries apply to the FDA or Canada Health, this is voluntary information," Gary Goodyear, the federal minister of science and technology, said Thursday in Montreal following a speech.

"So one, we don't feel that we need to threaten Canadians with punishment and how that would increase the validity or reliability of the census, so we've come out with a way that will provide the information we need without the threat or the intimidation."

The Canadian Council on Social Development says that while the Harper government is so far unmoved, "this battle is far from over." It added that despite "misinformation" from the government, the decision can be changed well into 2011. "It's not over until the surveys hit our mail boxes."

A previous attempt at overturning the decision through the Federal Court failed earlier this month.

A francophone group lost its legal challenge on Oct. 6, when its application for a judicial review of the government's decision was rejected.

The federation had argued that replacing the mandatory long-form census with a voluntary survey would yield less reliable information about francophone minority communities, and thus hamper the government's ability to fulfil its obligations under the Official Languages Act.

Judge Richard Boivin said the Official Languages Act does not mandate which tools the government must use when supporting and serving linguistic minorities.

Boivin backed the government's argument that it is too early to pass judgment on the usefulness of the voluntary survey.

Industry Minister Tony Clement has emphasized that measures will be taken to ensure as many Canadians as possible fill out the survey, to increase the reliability of the information.

The government argues that it has struck a balance between the need for data and concerns expressed by some Canadians that the census process was too invasive and unnecessarily coercive.