Chris Packham has filed a High Court legal challenge to the UK Government for a decision to weaken key climate policies.

The broadcaster and environmental campaigner has applied for a judicial review of the Government’s decision to ditch the timetable for phasing out petrol and diesel powered cars and vans, gas boilers, off-grid fossil fuel domestic heating and minimum energy ratings for homes.

A Department for Energy Security and Net Zero spokesperson said it rejects Mr Packham’s claims and will “robustly” defend the challenge.

The measures and their schedule had been set out in the Government’s Carbon Budget Delivery Plan, which was put before Parliament in March this year.

In September, Rishi Sunak announced he would delay the ban on selling new diesel and petrol cars from 2030 to 2035 and that 20% of households will be exempt from a new gas boiler ban among other changes, arguing that he does not want to burden ordinary people with the costs.

Following the announcement, Mr Packham wrote to Mr Sunak, the Energy Secretary and the Transport Secretary to challenge the decision, arguing that Mr Sunak does not have the legal right to change the timeline of carbon budget pledges at will, since the actioning of the Carbon Budget Delivery Plan is governed by statute.

Mr Packham said he did not receive a satisfactory response to his letter and, therefore, filed the judicial review application at the High Court.

He added that the Government’s response to his letter made clear that the decision was made without any public consultation, without informing the Climate Change Committee, without informing Parliament and without providing any reasons for the delays to the policies.

The grounds for his judicial review include obligations under various sections of the Climate Change Act, he said.

The legal challenge cites the requirement to have plans in place to meet the budgets if the proposals and policies within them are altered.

Mr Packham argues that the secretaries of state have breached this obligation by not confirming or outlining how they still intend to meet the latest budget.

The legal challenge also alleges that there was a failure to consult on the changes, particularly a failure to take into account ongoing consultations about off-grid heating and minimum energy efficiency in rental properties.

It also claims that the decisions were based on misinformation, such as the Government’s argument that the UK’s “over delivery” on previous greenhouse gas reduction targets meant that some measures were no longer needed, that carbon budgets “impose unacceptable costs on hard-pressed British families … that no-one was ever told about” and that the latest budget was “voted through with barely any consideration given the hard choices needed to fulfil it”.

Mr Packham argues that this messaging is wrong, because under section 10 of the Climate Change Act, the financing and social impact of the policies were taken into account when setting the sixth carbon budget

The legal challenge also alleges that there was a breach of the duty to inform the public of the reasons for the decisions to change the policies.

Mr Packham said: “We are in a crisis which threatens the whole world, everything living is in danger, including all of us.

“We have the potential to reduce that threat, we have the solutions and we have plans and targets. We must not divert from these.

“To do so on a whim for short term political gain is reckless and betrays a disregard for the future security of the planet.”

Mr Packham argued that the emissions reductions from the vehicle and gas boiler policies were “intrinsically important to the UK’s ability to reach somewhere near its net zero commitments”.

He said: “They should not have been changed without proper process and consultation. I believe that action was unlawful.”

Rowan Smith, a solicitor at Leigh Day, said: “If the Government’s lawyers are correct, then the Secretary of State would have carte blanche to rip up climate change policy at the drop of the hat, without any repercussions whatsoever.

“Chris and his supporters believe that would be an acute abuse of process, made even worse at the time of climate and ecological breakdown.

“That’s why this legal challenge is so important: if successful, it will mean that the Secretary of State has to keep to their promises to have in place policies that will enable carbon budgets to be met.”

Leigh Day said it has instructed barristers David Wolfe KC, Catherine Dobson and Toby Fisher for the legal challenge.

It comes after a successful legal challenge by Friends of the Earth that the 2021 sixth carbon budget did not include sufficient detail in order to demonstrate how the UK would reach net zero by 2050 as the Climate Change Act 2008 says it must.

A spokesperson for the Department for Energy Security and Net Zero said: “We strongly reject these claims and will be robustly defending this challenge.

“We have overdelivered on every carbon budget to date and these changes keep us on track to meet our legal net zero commitments. We routinely publish future emissions projections across all sectors and will continue to do so.

“Recent independent Climate Change Committee analysis shows our more pragmatic approach has no material difference on our progress to cut emissions.

“Households will now have more time to make the transition saving some families thousands of pounds at a time when cost of living is high.”