The Nobel Peace prize-winning lawyer, Shirin Ebadi, has complained to Iran’s judiciary that criminals are treated better than political prisoners.
She said the fact bail for an accused rapist was set 50 times lower than for a detained reporter reflected political interference in the judiciary.
Parnaz Azima, a US-Iranian journalist, was released but cannot leave Iran.
Ms Ebadi said if Iranians were silent about social justice and poverty, it was a silence of oppression, not calm.
Ms Ebadi is one of the few dissenting voices in Iran still speaking out in an atmosphere where most are frightened to be critical.
Political interference
In a letter to the head of the judiciary, Ayatollah Hashemi Shahroudi, Ms Ebadi complained that a confessed rapist had been treated more leniently than Ms Azima, who has been accused of producing propaganda against the Islamic state.
Bail was set for the Radio Free Europe journalist at $500,000 (£250,214), 50 times that of a rapist, and she had her passport confiscated.
The Nobel laureate is representing another US-Iranian detainee - the 67-year-old academic, Haleh Esfandiari.
However, Ms Ebadi still has not been able to see her client.
She said Ms Esfandiari called her mother from jail to say she was being held in solitary confinement in stifling heat and with an injured arm.
The call only lasted one minute, but Ms Esfandiari’s voice was said to be weak.
The cases of four US-Iranians being detained in Iran are being closely watched from Washington.
But at a seminar on peace, Mrs Ebadi also spoke of teachers, civil servants and workers arrested in Iran for demanding higher salaries.
She called for the release of several students arrested for expressing their views and, in a thinly veiled criticism of President Mahmoud Ahmadinejad, she said winning an election did not confer the right to rule without respect for human rights.
