​A Manitoba politician who was kicked out of the governing Progressive Conservative caucus is asking a judge to strike down the province's ban on floor-crossing as a violation of his charter rights.

Steven Fletcher is taking the province to court over a 2006 law that prevents him from joining another party and requires him to sit as an Independent until a byelection in his constituency or a general election. Fletcher says the law is the only one of its kind in Canada.

"As a result of my expulsion ... I am not able to represent the constituents of my riding to full advantage," Fletcher writes in an affidavit filed with the Court of Queen's Bench on Monday.

"If I were able to join three or more other members of the legislative assembly in a recognized political party, I would regain parliamentary privileges including ... asking questions to the full extent contemplated by the rules."

No one from the Tory government was immediately available to comment after the court documents were filed.

Fletcher, a former junior federal cabinet minister first elected to the Manitoba legislature last year, was punted from the Tory caucus in June after criticizing a law to create a new Crown agency to promote energy efficiency. He tied up two public hearings on the bill by asking questions late into the night before it passed final reading.

As an Independent, Fletcher lacks some of the rights that members of party caucuses have, including the ability to sit and vote on legislature committees and the right to ensure some bills come to a vote each session.

He also has fewer opportunities to ask questions in question period and, according to his affidavit, cannot issue income-tax receipts to donors because he does not represent a registered party.

Violation of free expression, association: lawyer

The law that bans politicians from crossing the floor was introduced in 2006 by the NDP government of the day. It came soon after federal MP David Emerson crossed the floor of Parliament to the Conservative Party, mere days after being elected as a Liberal.

Then-premier Gary Doer said the ban on floor-crossing was needed to respect the wishes of voters at the ballot box.

Bill Gange, Fletcher's lawyer, said the law violates his client's democratic rights, as well as his rights to free expression and free association under the Charter of Rights and Freedoms.

"His right to have his voice heard in the legislature has been affected," Gange said.

Fletcher's ability to join another caucus would not mean much to the Tories, who still have 39 of 57 legislature seats. But if he were to join the Liberals, it would give the struggling party a fourth seat — enough for official party status and the funding that comes with it.

Fletcher said recently he has no intention of joining another party and wants to fight the law on principle.