HALIFAX - The federal government's decision to scrap the long-form census constitutes a violation of Charter of Rights and Freedoms, a lawyer representing a coalition of Atlantic aboriginals told Federal Court on Monday.

Anne Smith said the shorter replacement for the mandatory, long-form census -- the voluntary national household survey -- will produce skewed data.

"It's not a representative survey if it's not mandatory," Smith told the court.

As a result, it will be difficult for the government to discharge its constitutional duties to aboriginal peoples, she said.

The lawyer said about 98 per cent of the long forms are filled out and returned, but only about 40 to 50 per cent of voluntary surveys are ever returned.

She said the data resulting from a smaller sample size could prompt the government to conclude that services are no longer required for aboriginal people.

"If you're not counted, then no one is accountable to you," Smith told Judge Russel Zinn.

"How can the government honour its duties to people ... if they don't know they exist?"

However, the judge questioned whether there would be any adverse affect on aboriginals if he allowed the voluntary, short-form survey to go ahead.

"I just don't see the prejudice," Zinn said, adding that he could order the government to use the mandatory, long-form next year. "I don't see why the court should stop them from doing it."

Smith said asking aboriginals to complete another survey would be counterproductive.

"People are already bombarded with calls from people ... seeking data," she said.

Smith went on to suggest that aboriginals enjoy a special relationship with the federal government through a concept known as the honour of the Crown. That concept means the government has a duty to consult when implementing legal changes that could affect native peoples, she said.

In this case, the Conservatives never consulted aboriginals and never explained why they were changing the census process, Smith added.

The aboriginal groups would like the court to issue an injunction stopping the new survey, as well as stopping any steps that would make it harder to bring back the long-form census.

They're asking that the court direct the government to reinstate the long-form census, or else insert more questions about aboriginal ancestry into the mandatory, short-form census.

The Harper government cut the long-form census over the summer, arguing it was striking a balance between the need for reliable data and the right of Canadians to refuse to divulge personal information.

The 2011 short-form census -- with its basic questions about gender, date of birth and language -- will remain mandatory, with the threat of fines for non-responders.

The new, voluntary national household survey has been criticized by hundreds of other organizations, municipalities and some provinces.

Critics have argued that the voluntary nature of the questionnaire will skew the data. As well, they say they are worried about the loss of information about groups that are least likely to fill out forms, including low-income Canadians and aboriginals.

A previous request for a judicial review by a francophone organization failed when a Federal Court judge ruled against the argument that the long-form census was the only reliable source of information about minority French-speaking communities.

The organizations involved in the latest Federal Court case all represent off-reserve natives. They include: the Native Council of Nova Scotia; the New Brunswick Aboriginal Peoples Council; the Native Council of Prince Edward Island and the Maritime Aboriginal Peoples Council.

Three Atlantic chiefs are also part of the court application.