An opposition MP says a decision rendering his private member's bill on the definition of marriage open to debate, but not to a vote, is a strike against democracy.

With the issue before the Supreme Court of Canada, Conservative MP Rob Moore introduced Private Member's Bill C-268 last week, calling for a House of Commons vote on the definition of marriage as a union of one man and one woman.

On Thursday, the Subcommittee on Private Members' Business ruled the bill non-votable.

Moore says he plans to appeal the decision.

"My bill was the only one out of 30 that was deemed non-votable," the New Brunswick MP said in an interview with CTV Newsnet.

"In this age when we're supposed to be addressing the democratic deficit, all private member's bill are supposed to be votable."

Under new standing rules of this minority government, all private member's bills are considered votable in the House, unless deemed otherwise by an all-party subcommittee.

For Moore, the fact his bill has been singled out is vexing.

"Rather than something in camera, with the Subcommittee acting as a court... our party's position has always been that the issue should be before the House of Commons."

Putting it to elected officials, Moore says, is the only way to ensure a decision is reached, "in a fair, open and transparent manner."

"What has happened has undermined that."

After a lottery selection, Moore was the fourth of 30 MPs selected to have their private member's business debated in the Commons.

Its contentious subject matter, however, posed a particular political challenge for Prime Minister Paul Martin's Liberal minority.

That's because the last time the issue was put to a vote in the House, when the Liberals held a strong majority in 2003, it was only narrowly defeated. Four years earlier, an identical motion defining marriage as the "union of one man and one woman, to the exclusion of all others," passed with a margin of 216 to 55.

According to Ipsos-Reid pollster John Wright, Moore's tabling of the private member's bill would have served to highlight the divisions that run through all the parties' ranks.

But it would not have necessarily translated into political points for his party.

"The areas in which the Conservatives have to grow in this country are primarily B.C. Ontario and Quebec," Wright said. "And those are the regions that have the greatest propensity for having more support for the concept."

In an interview with CTV, Wright said the strategy would not seem to propel the Conservatives into the arms of new supporters.

"If they want to be painted as intolerant by those who would like to vote Conservative, but have problems with this position it's not got a lot of upside."

Across Canada, courts in seven provinces and territories have called the current definition of marriage, as the union of a man and a woman, unconstitutional.