Rick Scannell was the second government-appointed defence lawyer to resign after the House of Lords, sitting as the country's highest court, said in December the anti-terror laws breached international human rights rules.
"It is in my view intolerable that the government should sit on a decision like this," he told BBC radio on Monday. "To my mind the action that it should take is very, very simple: It should release them."
Scannell published his resignation letter in several newspapers on Monday.
He said he had not quit at the same time as fellow special defence lawyer Ian Macdonald - who resigned just days after the House of Lords' decision - because he wanted to give the government time to react to the ruling.
"Unfortunately the initial optimism that I had that the government might, upon reflection, actually change its mind and not seek the continued detention of these men ... proved to be misplaced," Scannell said.
He declined to comment on reports that all the special defence lawyers had decided to resign in protest.
The UK still holds 11 suspects
under the legislations
After the 11 September 2001 attacks in the US, Britain, like many other countries, gave itself special powers to detain without trial foreigners suspected of "terrorism".
The government does not have to prove they committed a crime, only that the authorities have "reasonable grounds" to suspect that they might pose a threat.
Britain, which has said it will review the legislation after the Lords' decision, has used the powers to detain a total of 17 foreigners, saying it has "reasonable grounds to suspect" they are linked to Usama bin Ladin's al-Qaida network.
Britain still holds 11 suspects under the laws and the authorities say they will not free them until parliament has reviewed the laws.