In a hearing room on the 11th floor of the High Court of Riyadh, two professors and a poet have been standing trial, sometimes drawing overflow crowds of people eager to monitor a case that could alter the pace of political reform in the kingdom.

The defendants face charges that by petitioning for democratic change in a country ruled for its entire 72-year history by the Saud royal family, they are undermining the government as it confronts an armed threat from Muslim militants.

What sets the case apart from scores of others involving Saudi dissidents is that for the first time the proceedings are being held in open court and watched closely by the Saudi news media, human rights activists, foreign diplomats and friends and families of the accused. It has become a venue for a group of Islamic defense attorneys, many of them former political prisoners themselves, who are arguing that the government has misinterpreted the Koran, the constitution in Islam's birthplace, by ignoring principles that they say allow the kinds of reforms the defendants are advocating.

The case illustrates the challenge facing the royal family as it edges open a closed system in hopes of reducing mounting social frustrations within the kingdom, while trying to maintain a tight hold on ultimate authority.

Roughly 50 people have been killed in the kingdom this year in bombings and clashes between Saudi security forces and Muslim militants, violence that the royal family and democracy advocates agree makes reform both more urgent and difficult to carry out.

"This trial should be seen as not only something for the Saudi people, but also as an opportunity for the royal family," said Mohsen Awajy, a reform advocate who was jailed by the government for four years in the 1990s for advocating political changes, and who has signed the defendants' petition. "These three men are not criminals, and by intellectuals and even some princes who want reform, they should be seen as heroes. History has shown no mercy on dictators."

Other reforms the government is cautiously trying out include municipal elections scheduled for November, the first free balloting in four decades. The country's appointed consultative council recently received new powers to propose laws, examine public spending and question government ministers. Recent official decrees have encouraged Saudi women to take a greater role in society.

The men on trial are Ali Dimeeni, a poet and former Marxist; Abdullah Hamed, a leading Islamic human rights activist fired from his university teaching post for his political views; and Matrouk Faleh, a professor of comparative politics at King Saud University with a doctorate from the University of Kansas.

Each represents a distinct element within the kingdom's diffuse reform movement, which is mostly a mix of orthodox Muslims and foreign-educated intellectuals and technocrats. The factions often work independently, and have struggled to outline a joint plan in their campaign against the government.

The men were seized in March in a wave of arrests in Jiddah, a relatively progressive commercial hub on the Red Sea, the eastern city of Dammam and other communities. The Interior Ministry, which oversees the kingdom's domestic security organizations, said it arrested the men for "issuing statements that do not serve the unity of the homeland or the integrity of the society."

Specifically, the men were circulating petitions calling on the royal family to create a constitutional monarchy and an independent judiciary, allow open parliamentary elections and form an independent human rights organization to replace a government-appointed commission created this year. Roughly 140 people signed the petition, which is still being circulated underground.

The State Department condemned the arrests, which came within a week of a scheduled visit by Secretary of State Colin L. Powell, as "inconsistent with the kind of forward progress that reform-minded people are looking for."

Less than a week later, 10 of the detained were released after agreeing to government demands that they stop circulating the petition and refrain from speaking to the news media. Dimeeni, Hamed and Faleh, all husbands and fathers, refused, and charges were brought against them. They are being held in an old villa in the capital that has been turned into a small prison.

The case has exposed divisions within the reform movement. While admiring the prisoners' stand, many in the movement say the men are pushing too hard and that change should come slowly and from the royal family itself, not from a grass-roots movement that could end up weakening the government.

"This trial is a training exercise not only for the government, but for the reformers as well," said Abdulaziz Alsebail, a professor of modern literature at King Saud University who has long been active in the reform movement. "Implicitly, we agree with these people. The point is whether this is the right way to do this."

The hearings are also being studied for what they might divulge about the competing reform currents within the royal family. Despite the family's octogenarian leadership, many Saudi reformers and Western diplomats say it is more open to democratic reform than most of the kingdom's 25 million citizens.

In the past, the government has cited national security in closing political trials. But this time the trial is open, and the men have been given access to attorneys. "This is in part to show the seriousness of the government's effort to make reforms," said an Interior Ministry official. "It is a step in the right direction to prove that we intend to carry out changes, as we have promised."

The second hearing in the case was scheduled to be held earlier this month, but several hundred people swamped the 30-seat courtroom, prompting the three-judge panel to postpone the hearing indefinitely. Some in the crowd, which extended into the hallways, broke into chants of "Reform, reform."

That spectacle led some members of the reform movement to worry that hard-line agencies such as the Interior Ministry might close the rest of the proceedings.

"If the government, in its calculus of the outcome of the trial, feels it didn't gain much, it may go back to its old ways," said Abdel Aziz Abu Hamad, a former investigator in for Human Rights Watch in Saudi Arabia.

In a large corner office in a glass-and-steel tower one recent day, the defense team ate dates, drank bitter Arabic coffee and plotted a strategy that challenges the Islamic underpinnings of the royal family's claim to power. A huge curving mahogany desk was in one corner, and a bookcase filled with legal texts lined one wall. Two wall-length windows provided a view of Riyadh's skyline.

The nine lawyers, many of them wearing the fringe of beard marking them as pious Muslims, were trained sharia, a largely unwritten legal code based on the Koran. They belong to what they describe as a widening political movement called Islah, meaning "To Correct." The group says it is funded mostly by Saudi exiles in London, and the lawyers are working on the case pro bono.

Their legal challenge to the royal family on Islamic grounds is a novel one, designed to deprive the government of a time-tested defense that its monopoly on authority is sanctioned by Islam.

"Our view is that there is no objection between Islam and Western democracy in the matter of elections and human rights," said Abdulrahman Lahim , 33, a defense attorney who was jailed for nine days last spring for speaking to al-Jazeera television about the arrests. "This is a new generation with a new view of democracy and Islam."

Every Wednesday, Jamila Elukla, her three children and five-month-old grandson travel from their comfortable home in a walled faculty compound near King Saud University to Olaisha Prison, where her husband, Faleh, has been held nearly every day since plainclothes policemen arrested him at his campus office five months ago.

Elukla and Faleh are from Jouf, a desert town near the Jordanian border. They moved to Riyadh in the 1970s, when Faleh took a teaching post at the university. Not long after, the couple traveled to Lawrence, Kan., where they lived for nine years while Faleh worked on his PhD in political science. Two of their children were born there and are U.S. citizens.

Faleh and his family returned to Riyadh 17 years ago, and he was a respected and mostly uncontroversial professor until his arrest. His wife says his religion is important to him, but is not the foundation of his political views.

His spotless home, filled with family photos, is part of a grid of tan villas that have few windows but many elegant cars parked in garages that are perks of the Saudi middle class. One recent day, Elukla, 47, peered from inside her black covering with large dark eyes as she received a visitor. She said her husband, 54, is making his stand now because of the rising violence she sees around her. "We don't want radicalism, we don't want violence," Elukla said. "If you love your nation, you work for it."