The government is facing a backlash over controversial proposals to remove juries from some inquests.
The case of Azelle Rodney has prompted calls for reform of the law
Provisions in its counter-terrorism bill, published last month, would also allow home secretaries to replace coroners with their own appointees.
Ministers insist the new powers would be used sparingly and the vast majority of inquests will still stay public.
But critics say the changes are dangerous and unnecessary meddling with a system that has worked for centuries.
A little-noticed clause in the bill would allow the home secretary to prevent a jury being called to an inquest and even to change the coroner for "reasons of national security".
The change is intended to avoid the risk of sensitive information - such as details of phone-taps or surveillance operations - being revealed to jurors and other members of the public.
But it is not explicitly restricted to terrorism cases and could in theory be applied to cases of deaths where no such link is suspected.
This opens up the possibility of juries being barred from sensitive inquests such as that into the death of Jean Charles De Menezes, the Brazilian man police shot because they thought he was a terrorist.
As the law stands, coroners must call an inquest into violent, unnatural or unexplained deaths in their districts. They are held in public and a jury must be convened if the death occurred in certain circumstances, including in police or prison custody.
Jury inquests account for just 2% of the total number.
The reform may have been triggered by the threat of a legal challenge to the government over the case of a man shot dead by police whose inquest cannot go ahead because some secret evidence cannot be made public.
Azelle Rodney, 24, was in a car under police surveillance when it was stopped by armed officers in London on 30 April, 2005. He was shot several times and died of his injuries.
Alan Beith, the Liberal Democrat chairman of the Commons justice committee, believes the reform is dangerous.
"I'm not comfortable with a situation where a politician is deciding there shouldn't be a jury in a particular inquest," he told BBC Radio 4's World This Weekend.
Mr Beith said the move addressed the genuine problem of how to handle security-based evidence in an inquest.
But he warned: "Simply tacking something on to a bill of this kind which does not address the fundamental problems in the coroners' system is a dangerous way to do it."
Shadow home secretary David Davis said: "I can see the point in the narrowly-defined group of terrorism inquests, inquests into deaths related to terrorism.
"When the Home Secretary wrote to me she said it would allow them to use intercept evidence in those cases.
"That being said, it will have to be very narrowly defined."
Opponents have already warned the reforms could breach the European Convention on Human Rights (ECHR) which requires judicial investigations to be independent of government.
But justice minister Bridget Prentice insisted it would ensure inquests comply with the ECHR, even when material cannot be disclosed publicly.
When this is the case, the coroner and lawyers will be able to see the material, she advised, adding: "The interests of the families can be fully represented by counsel to the inquest, and counsel will be able to see all the material in question."
The government published a draft coroners bill two years ago which stressed the importance of inquests being held in public, but it was not included in the Queen's Speech.
The new bill, which has yet to go before MPs, has already sparked intense debate about provisions to increase the amount of time terrorist suspects could be held without charge.