A second lawyer representing terrorism suspects held without charge in British jails has resigned.
Most of the detainees are held at Belmarsh maximum security jail
A month after the House of Lords said the system broke human rights laws, it was "intolerable" the men had not been released, said Rick Scannell.
He said he had not resigned with his colleague Ian Macdonald QC at the time because he hoped the government would rethink its position.
Nine foreign nationals are still held without trial under anti-terror laws.
The Anti-Terrorism, Crimes and Security Act of 2001 (ACSA) allows foreign terror suspects who refuse to be deported to be jailed without trial in the UK.
In December the House of Lords declared ACSA to be incompatible with European human rights laws.
"At the time I hoped the government would react positively and release the men," Mr Scannell told BBC Radio 4's Today programme.
But he said the fact lawyers were still being given instructions and the fact reviews into the detentions were pending persuaded him otherwise. "It has been a little over a month now since the House of Lords gave their landmark decision, emphasising the fundamental importance of the right to liberty," he said.
"It is, in my view, intolerable that the government should sit on a decision like this."
Human rights demonstrators have condemned the detentions
In his letter to Attorney General Lord Goldsmith he said the detainees should be released or be charged and detained within the criminal system.
A number of special advocates represent the detainees at the Special Immigration Appeals Commission (SIAC), but are forbidden from discussing key evidence with their clients.
Mr Scannell declined to comment on a newspaper report that all advocates had met and decided they would all resign if the government ignored the ruling.
Following the Lords' decision, Home Secretary Charles Clarke said the nine men would remain in prison.
He said the government would look at ways of modifying the legislation to address the Lords' concerns.
The Guardian newspaper reported on Monday that the government plans to announce changes to the anti-terror laws next week, but the Home Office declined to comment on the story.
Seventeen people have been detained under ACSA powers since 2001.
The government points out they are free to leave the country at any point.