Britain could become the first country to set legally binding carbon reduction targets under plans unveiled by Environment Secretary David Miliband.
Mr Miliband said annual targets would not be 'sensible'
The draft Climate Change Bill calls for an independent panel to set ministers a "carbon budget" every five years, in a bid to cut emissions by 60% by 2050.
If they miss the figure, future governments could be taken to court.
The Tories and Lib Dems welcomed the proposals, but said carbon budgets should be set annually.
Mr Miliband has said annual targets would be too rigid to make allowances for climate variations.
He hailed the draft bill as "the first of its kind in any country", and said Britain was "leading by example".
The draft legislation will go to public and parliamentary consultation before becoming law next year, but environmental campaigners want to raise the 2050 target to 80% and set annual 3% cut targets to ensure compliance.
Shadow environment secretary Peter Ainsworth, for the Conservatives, said the proposals were a "welcome step forward," although he said some "key elements" were missing at present.
"We would like to see a system of rolling annual rate of change targets - rather than targets set for five-year periods - to ensure that the UK remains on track towards a low carbon economy and to ensure true accountability.
"There is a danger that the five-year approach will enable responsibility for failure to be shunted on from one government to another."
But he added it would be a "great help" in international climate change negotiations "to be able to say, 'look we are making binding legal commitments".
The carbon reduction targets will be based on advice by an independent committee.
If future governments fail to achieve the targets, they could be taken to court, with a judicial review deciding what punishment - if any - to hand out.
The draft bill does not stipulate how the cuts should be made, or give specific reduction targets for individual businesses, councils and households.
Mr Miliband said there were "big decisions" to be made on issues such as using nuclear power.
He added: "In the end I don't care where the carbon reduction comes from. It's about the public interest and the market finding it."
The government plans include:
Targets to reduce carbon emissions by 60% by 2050, from 1990 levels, and between 26% and 32% by 2020
Greater energy efficiency, with more consumers becoming "producers" of their own energy at home
Investment in low-carbon fuels and technologies, such as carbon capture and storage, wind, wave and solar power
Carbon "budgets" - which cap emissions levels - set every five years
The government reporting annually to Parliament on its progress in controlling emissions
Future policies to control emissions would also be made "quicker and easier" to introduce.
A full Climate Change Bill is set to be published in the autumn.
At the weekend, the Conservatives unveiled environmental proposals including VAT or fuel duty on domestic flights.
But Mr Miliband said more focus was needed on cutting carbon emissions from homes, citing government plans to make all new houses carbon-neutral by 2016 and encourage the use of energy-efficient light bulbs.
The Liberal Democrats said they broadly supported the aims of the climate change bill but urged closer monitoring of a government's green progress.
The party's environment spokesman Chris Huhne said: "There is a possibility here that the government wouldn't really be held to account for what it had done or had failed to do until after it had faced the electorate again and that's not a satisfactory situation."
The Green Party said setting a legal framework for carbon emissions was a "massive opportunity" but the proposed targets were "dangerously unambitious".
Principal speaker Sian Berry added: "We have heard the rhetoric about renewables and energy efficiency many times before.
"It won't happen without real action, and current government support for renewable energy has descended into a farce."
Former environment minister and Labour leadership hopeful, Michael Meacher, said that although the bill had long-term goals, it lacked short-term targets "as evidence that we are actually on track".
He said it was also "disappointing" that the draft bill lacked policies on airport expansion, car emissions and carbon allowances for private households.
Meanwhile, former minister Peter Kilfoyle has called on Britain to co-operate with American states, such as California which has led efforts to reduce pollution, rather than its central government in Washington.
He told MPs in a Westminster Hall debate the "special relationship" between the two countries was beneficial when it came to the environment.