Abdollah Nouri was one of the young stars of the Iranian revolution's early years, a cleric so loyal to the government he was tapped by Ayatollah Ruhollah Khomeini as a personal liaison to help oversee projects as diverse as rural development and national security.

But Khomeini is gone, and things are no longer so black and white. There is a fight underway for the future of this country, and it is in part the ideas and actions of onetime loyalists such as Nouri that are fueling the schism.

Nouri advocates a version of Islamic government that emphasizes free debate, democracy and tolerance--the "Islam of love," he calls it. For using his newspaper, Khordad, to promote this vision, Nouri has been charged with sullying Khomeini's legacy by offending Islamic values. He has been hauled before a special clerical court that the late leader established outside the country's formal legal structure to deal with such matters. It has the power to impose a range of punishments, including barring Nouri from parliament.

In response, Nouri has used his defense to launch an attack on the Iranian system itself, arguing that no system should allow its leaders to be above criticism. To a once secret courtroom of mullahs, sitting in a converted living room in a north Tehran mansion, Nouri brought a torrent of flashing cameras and feisty free thinking, clear evidence of the challenge Iran's government faces from some of its once favored sons.

The court "perceives it has legitimacy through the leader," Nouri said in his opening remarks, referring to Ayatollah Ali Khamenei, who assumed the role of supreme leader on Khomeini's death. "But even the leader cannot act above the law."

With words like these, Nouri has turned a formerly obscure courtroom into a prime example of how Iran's revolutionary system is straining under a theological and political challenge from a growing number of citizens yearning for social liberalization, the rule of law and a government and economy more closely linked to the rest of the world. He has set up a dynamic that some here have compared to the battles over secular and clerical legitimacy that were fought in Europe centuries ago.

With the neatly trimmed beard and glasses that seem standard among Iran's clerical class, Nouri has drawn a following among Tehran's intelligentsia, and also among the general public. He was the leading vote-getter in recent Tehran municipal elections and has announced plans to run for speaker of parliament in elections in February.

In the West, the easy smiles and democratic ideas of the reformist president, Mohammed Khatemi, are the most familiar evidence of the questioning underway. Khatemi is also an influential cleric, and his call for a "dialogue of civilizations" has put a milder face on the policies of a nation more associated in the United States with the 1979 seizure of the U.S. Embassy here and international terrorism.

But his upset election in May 1997 is only one aspect of a movement that has become broadly popular among Iran's youthful, 60 million-strong population. And the movement has become as deep as it is broad, driven by a rethinking of Islamic government among a core of academics and clerics whose questions have been embraced by a wide segment of the population.

The religious hierarchy has fought back vigorously, closing several leading liberal newspapers this year, impeaching members of Khatemi's cabinet--including Nouri, who was interior minister--and jailing or silencing dissident clerics. On Nov. 11, the jury in Nouri's case recommended a guilty verdict. That decision, if upheld by the judges who have final say, would likely lead to the closing of his newspaper and perhaps the banning of his candidacy for parliament.

Despite the backlash, many Iranian and diplomatic analysts in Tehran see the country continuing to liberalize. The main questions, they say, are how fast the process unfolds, how strongly the upcoming elections reinforce the trend and whether hard-line factions become desperate enough to use their command of the military and the security services, including street militias, to force the outcome.

"They can't stop the thought. The thought is there," said a 20-year-old math student, who would only provide his first name, Hoten, during a recent lecture on Islamic philosophy.

In Iranian politics and government, however, few things are certain. Even though Khatemi's electoral mandate was large, and his popularity continues to hold, he wields only partial control over the reins of power. The country has, in effect, two governments--one run by Khatemi and his ministries and one headed by Khamenei that intertwines, overlaps and supervises the other.

For example, the courts in theory fall under Khamenei's direction. Tehran's formal legal code is enforced by three court systems set up by the constitution: a public court that tries routine civil and criminal matters; a press court to enforce new laws regulating the media; and a revolutionary court that tries matters deemed to violate revolutionary principles.

The clerical court trying Nouri, however, is a fourth entity, not mentioned in the constitution, and apparently with no formal legal code to administer.

Khamenei also has the authority to check the work of parliament and control electoral opposition. A 12-member Guardian Council, which he appoints, must approve any candidate for the legislature or president. It also reviews legislation for compliance with the constitution and Islamic principles.

The council's role in the upcoming parliamentary vote is already causing controversy, with reformers expecting top candidates--such as Nouri--to be blocked from running.

On security matters, Khamenei's power is even more complete. He is commander in chief of the armed forces and also controls the Revolutionary Guards, the government's loyalist shock troops. He also has moral authority over what amounts to quasi-governmental units such as the Basij volunteers, who have historically been used to enforce public morality and other religious edicts.

While Khatemi is ostensibly in charge of some internal security forces through the interior and other ministries, even that shows the conflicting forces at work inside the government. It was on Khatemi's watch that a number of security officers began murdering dissident writers in an apparent effort to destabilize his government.

Outside the organs of power, the fervor for change is clearly visible. In a Tehran home recently, in a large room furnished with a single desk and several Persian rugs, some 300 Iranians of all ages sat silently listening to a soft-voiced philosophy professor who at one time was a revolutionary firebrand but has become a theoretician of dissent.

Abdel Karim Soroosh served on the cultural council that ordered Tehran University closed for two years in the aftermath of the revolution. Later, he said, when he listened to the leader of a Friday prayer service call on those in attendance to attack an opposition group, he began to rethink the principles of the revolution, and of Islamic government generally.

His thinking so challenged the system that he has been forbidden from teaching. But his ideas circulate widely through lectures each Wednesday night. Using the methods of Western literary critics, he has argued that the statements of Islamic leaders dating back to the Prophet Muhammad must be interpreted in the context of their times, an attitude that frees modern leaders to update Islamic teaching as needed and distinguish between the "essentials" of their religion and its historical "accidents."

During the revolution, "I was under the control of my passions, and you know, revolution is not rational," Soroosh said in an interview. "All of us were very emotional. . . . Now we are looking at everything through the dry eyes of reason, and trying not to take anything as holy or beyond criticism."

That includes Khamenei's authority and the notion that he, and the vast power structure he controls, should be subject to the constitution and made popularly accountable. This, more than anything, is at the center of the struggle for Iran's future.

The battleground extends down to basic notions like free expression. The social atmosphere continues to lighten and the number of daily newspapers has expanded under Khatemi from a tightly controlled few to more than a dozen of all ideological stripes. It also includes reform of the court system and relations with the West, particularly the United States.

There is hope among the dissenters for economic reform as well. Blessed with vast oil wealth but beleaguered by 25 percent inflation, Iran has an immense population of youth who need jobs and a sclerotic, state-oriented economy. And, the reformers say, the government must get control of a network of Islamic charities that manage as much as one-third of the economy and operate beyond public scrutiny.

All of those issues ultimately revolve around how much power should rest in the hands of Khamenei, a figure who as "Guardian of the Faithful" has a moral authority believed, among his advocates, to be infallible. It is an issue still only hesitantly approached in public.

When students demonstrating over the closure of a liberal newspaper this summer began criticizing the leader directly, it was a rare breach of Iran's political etiquette, and, for the system, a nervous moment. The immediate resolution of that conflict seemed to bode ill for the reform movement, as Khatemi and Khamenei closed ranks to organize a massive demonstration supporting the system. But the weeks following have led some to a different conclusion.

Khamenei has, on several occasions, voiced his support for Khatemi and Khatemi's principles. He emphasized the rule of law, for example, when a chief security officer vowed to take private vengeance against four students charged with apostasy for a satiric article in an obscure college publication. Although ultimately sentenced to three years in prison, the four were spared the death sentence that hard-liners had demanded.

"The conservatives are really strong" and, if threatened, could respond with enough arrests and repression to set the process back several years, said Mohammad Hadi Semati, a political science professor at Tehran University. "But they are beginning to act in the framework Khatemi has set up. . . . The willingness to suppress is eroding. In the long run we expect the process will go on, inch by inch, cat and mouse, reform from within."

CAPTION: How Power Flows in Iran (This graphic was not available)

CAPTION: Iranian cleric Abdollah Nouri attends his trial at a special clerical court, where he is charged with offending Islam.

CAPTION: A woman holds posters supporting Iranian President Mohammed Khatemi and reformist cleric Abdollah Nouri. A liberal reform movement would like to take power over the government out of the hands of Islamic religious leaders.