TEHRAN -- President Mahmoud Ahmadinejad said he was delighted when reformist students disrupted his visit to their elite university in December, burning his portrait and shouting "Death to the dictator!"
It showed the world that Iranians can protest "with an absolute, total freedom," the hard-line president wrote on his website.
But at least eight of Amir Kabir University's leading reformists have been arrested since May, according to their lawyers and activists inside and outside Iran.
They are among hundreds rounded up in recent months in a nationwide crackdown on those accused of threatening the system.
Two years after Ahmadinejad's election, the "Tehran Spring" of his moderate predecessor, Mohammad Khatami, is a fading memory. A deep chill has settled over those pushing for change inside the Islamic Republic.
Some dissenters attribute the crackdown to the regime's fear of a US effort to undermine it as tensions over Iran's nuclear program intensify. Others say the intent is simply to contain discontent fueled by a faltering economy.
Teachers, feminists, union leaders, journalists, students, and at least four Iranian-Americans have been arrested over roughly the past six months.
Most have been freed after spending days, week, or months behind bars. But many of their cases remain open in Iran's revolutionary courts, a parallel justice system that operates with few of the protections available in civilian courts, lawyers and activists said.
"The new government has increased pressures on the nation -- students, laborers, intellectuals," said Ebrahim Yazdi, foreign minister after Ayatollah Ruhollah Khomeini's 1979 revolution and now leader of the banned but tolerated Freedom Movement of Iran.
"When laborers stage protest rallies, the government, instead of talking to them, takes them to jail. Women are jailed just for collecting signatures in support of women's rights," he said.
Restrictions in Iran are far from absolute. Iranians criticize the government in public and ignore a wide array of social regulations at home. Defenders of the system counter that it is more open than in many nations in the region, including some of America's allies.
Iranian officials say the judiciary is simply prosecuting crimes. "Thank God, in Iran the rule of law prevails and the judiciary of the Islamic Republic is an independent branch," Ahmadinejad said at a news conference.
But the crackdown goes beyond the justice system. Books are more closely censored these days, and newspaper editors are being told how to cover issues ranging from nuclear negotiations to crime control.
"This is completely new, " said Mashaallah Shamsolvaezin, head of Iran's Association for Defense of Freedom of the Press.
The annual spring enforcement of Islamic dress codes in Tehran was stricter this year, spawning hundreds of arrests. Amnesty International said the number of executions rose from 94 in 2005 to 177 last year, most for nonpolitical offenses.
At least 33 women have been arrested in recent months at rallies seeking change on issues such as legalized polygamy, child custody, and a marriage age of 13, said Nasrin Sotoudeh, a lawyer for some of the women. About a third received suspended prison terms of several years.
Even the smoking of waterpipes in teashops, a beloved tradition, has been banned, officially for health reasons.
Campus poetry nights have been canceled, along with commemorations of past student uprisings. Bus drivers and other workers have been fired and arrested for union organizing, and nearly 300 teachers were arrested after demanding higher pay.
"Unfortunately our authorities declare any gathering which is not according to their wishes as being illegal," said Abdolfattah Soltani, a lawyer for bus drivers and teachers.
An unknown number of cases remain under investigation by the revolutionary court, keeping suspects unsure of their fate. "It's possible that others are being held in unofficial prisons," Solatani said.
The Freedom Party's public meetings have been banned for years. This year, supporters have been blocked from gathering even in a private house, Yazdi said.
American connections have come under particular scrutiny.
Haleh Esfandiari was one of four Iranian-Americans arrested while visiting Iran and charged with endangering national security. She directs the Middle East program at the Woodrow Wilson International Center for Scholars in Washington , D.C .
Parnaz Azima, a journalist who works for the US-funded Radio Farda, is free on bail, but she is barred from leaving the country.
Two men in custody are Kian Tajbakhsh, an urban planning consultant with George Soros' s Open Society Institute, and Ali Shakeri, a founding board member of the Center for Citizen Peacebuilding at the University of California, Irvine.
A judiciary spokesman said June 12 that a judge would complete his preliminary investigation of the four "within the next two or three days."
Yesterday, the spokesman, Alireza Jamshidi, said the investigation was still in its "final phases" and results would be announced in one or two weeks. The delay was not explained.