Changes that the Government is crafting to the way politically sensitive inquests are conducted must be stopped in their tracks. They give fresh ammunition to those cynics who say that justice must not only be seen to be done, sometimes it must be seen to be believed.

Under the skirts of the Counter-Terrorism Bill, the Government is aiming to give the Home Secretary discretion to hold in secret any inquests that - for reasons of national security, international relations or “any other public interest” - it would rather shield from public eyes and ears. Such inquests, which could include such sensitive cases as the one due to be held next month into the death of Jean Charles de Menezes, would instead be heard by specially vetted coroners in private, without a jury. In spite of shrill criticism from opposition parties and lawyers, the provisions have already tiptoed through the House of Commons with scarcely a murmur of publicity. They now come before the House of Lords this autumn. They should travel no farther.

The Government's far-reaching plan has understandably, and rightly, been branded a disgrace by Inquest, a group that offers advice on the inquest system alongside legal support to bereaved families. The concern is not just that suspicion inevitably festers in a legal system that is not as transparent as Cellophane. It is that the Government seeks to grant itself so elastic a definition of what might constitute the public interest that the new powers could allow it to steer behind closed doors potentially awkward inquests; such as, say, those into the deaths of Dr David Kelly, or the military victims of “friendly fire”. The worry is that the temptation will exist to conduct private inquests for reasons of political convenience rather than judicial expedience. Will every home secretary be able to resist?

Is it not conceivable that, had such powers been available at the time, the Government might have considered sparing itself the public embarrassment of February's inquest into the death of Captain James Philippson, at which its failure to supply him with basic equipment in Afghanistan in 2006 was condemned as “unforgivable and inexcusable”? The assistant coroner in Oxford conducting the case added that such failure constituted a breach of trust by the Ministry of Defence.

Secrecy may not skew the course of inquests, but may yet deprive families of full details of how loved ones died. In the case of the “friendly fire” that killed Lance Corporal of Horse Matty Hull when a convoy of tanks was attacked in Iraq by two American A10 Thunderbolts, it is not that the coroner's eventual verdict was flawed. It was not. Although the US had refused to declassify the cockpit records of the pilots for use in open court (they came to light only after The Sun obtained and published them), the coroner had in fact seen them, and thus the outcome of the inquest had not been prejudiced. But the coroner acknowledged that America's refusal to declassify the data had prejudiced the need, and moral entitlement, of Lance Corporal Hull's family to learn all there was to be known about his death.

Such cases should sound alarms for anyone wondering how the Government's new proposals might corrode the right of people to know how their loved ones died. When the Government has a licence to conduct its affairs in private, we can never be sure when it might be exercising that licence. And if the public do not know whether or not they are being kept in the dark, they will be tempted to behave like judicial hypochondriacs, forever fearing the worst. This is healthy neither for justice nor for government.

Open justice is a fundamental principle of English law. Agents of the State must not only be accountable, they must be seen to be accountable.