A private member's bill requiring the government to drastically cut greenhouse gases was approved by the House of Commons Wednesday.
NDP leader Jack Layton's bill passed third reading with the support of the Liberals and Bloc Quebecois.
The bill, which must go to the Senate before it receives royal assent, will require the government to cut greenhouse-gas emissions by 80 per cent below 1990 levels by 2050.
Ottawa must set interim reduction targets for every five years between 2015 and 2050, according to the bill. However, the minority Conservatives have a history of ignoring similar legislative attempts.
A private member's bill cannot propose the spending of public money. The House of Commons Procedure and Practice rules say: "The Crown alone initiates all public expenditure."
The bill closely mirrors the cuts required by the Kyoto Protocol, which Canada has signed on to.
It is the second time in less than a week, that the Conservative's plan to cut greenhouse gases has been undercut.
On Monday, Quebec and Ontario signed a historic agreement to cut greenhouse gases in Canada's two largest provinces.
The Quebec-Ontario deal will involve a basic framework for an inter-provincial cap-and-trade system -- with a 1990 baseline for emission levels. The system aims to limit industrial emissions by allowing companies to sell unused carbon credits to companies that exceed their cap.
Federal Environment Minister John Baird criticized the deal as a "scheme" and said it would be ineffective.
The Conservatives say their environmental plan will reduce emissions 20 per cent below 2006 levels by 2020. But environmentalists have overwhelmingly criticized the government's plan.
With files from The Canadian Press