Campaigners fear that the legal body designed to protect the environment on behalf of citizens is being undermined by the UK government.
Ministers promised that after Brexit, laws on air, water and waste would be policed by an independent Office for Environmental Protection (OEP).
Previously, these laws were enforced by European courts, which prosecuted EU governments that breached green rules.
Ministers promised the OEP would be similarly independent.
But they now want to grant themselves powers to “advise” the new body.
These plans were revealed in a tabled amendment to the Environment Bill.
Critics fear ministers may counsel the OEP against taking the government to court if it breaches laws.
Ruth Chambers from the umbrella group Greener UK told BBC News: “This provides a ‘get out of jail free’ card for the government to direct the watchdog away from awkward or inconvenient cases.
“It completely undermines claims that it will be independent.
“This is a clear and simple weakening of environmental protection. Our nature, air and water quality is being put at further risk. We urge ministers to reconsider.”
The government insists it’s committed to ensuring the independence of the OEP.
It says the body should gain greatest benefit by focusing its prosecutions on the most serious cases.
A spokesperson told BBC News: “The Environment Secretary will not be able to intervene in decision-making about specific or individual cases.
“The Bill will also ensure the new body will have the power to scrutinise environmental policy and law, investigate complaints and take enforcement action against public authorities where necessary.
But Greener UK’s concerns are echoed by Dr Stephanie Wray from the environmental consultancy RSK.
She told BBC News: “The government says the OEP should focus resources on the most serious cases. But this assumes that it is only big, high-profile cases that seriously affect the environment.
“In fact, small-scale chipping away at biodiversity, or myriad small breaches of air pollution limits, all add up.
“This would allow the government to potentially override the independence of the OEP by directing it towards or away from particular cases to suit political motives.
“Areas where the government was not meeting its targets, like waste, the circular economy, or the water framework directive, might be areas the OEP could be directed not to focus on.”
MPs are determined to ensure the legal framework for the new body is water-tight.
Two chairs of Parliamentary committees, Neil Parish (Environment, Food and Rural Affairs) and Philip Dunne (Environmental Audit Committee), have asked ministers for guarantees about its independence, governance and budget.
The government has already insisted that it will appoint the leadership of the OEP.
Nervous environmentalists remember the history of the Environment Agency, which was set up under statute to be independent.
“The Labour government said it wanted the agency to be a strong independent voice championing the environment,” said Becky Willis, professor in practice at the Lancaster Environment Centre.
“But subsequent governments got fed up of being criticised – so they basically silenced the agency over a period of time, and chairmen and women were told not to criticise ministers openly.”
The agency is now hugged so tight to government that its press enquiries are handled by the government itself.
Tom Burke, a former government adviser and the chair of think-tank E3G, told BBC News: “People would be right to be highly suspicious. Ministers made a promise on the independence of the OEP they knew they wouldn’t keep. Now they’re taking it back by stealth.
“The acid test will be whether the OEP gets its own website independent of government – if not, it will be compromised.”
The MPs have set a deadline of 6 November for a response from the Environment Secretary.
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