Hailed as "an important step" by the United States, the law's passage marked a turnabout by one of its strongest critics -- Vice President Adel Abdul-Mahdi, a member of one of the main Shiite political parties, the Supreme Council.

Mahdi sits on the presidential council along with Vice President Tariq Hashimi, a Sunni, and President Jalal Talabani, a Kurd. The council must approve all legislation passed by Parliament.

Mahdi, who said the law was unconstitutional, rejected it at first. He later reversed his decision and approved the law after being given assurances by senior members of Parliament that some of his concerns -- most notably, the central government's ability to sack local governors -- would be addressed in the future, he said.

The new law is seen as a victory for advocates of a strong central government in Iraq since -- in addition to setting an Oct. 1 deadline for new provincial elections -- it stipulates the dominance of federal law over local law, analysts say.

"It's one of the most important laws passed in recent years," said Raed Jarrar, an Iraqi consultant for the American Friends Service Committee. "It's as important as passing the Constitution. It draws the line between those who want to weaken the central government and turn Iraq into a confederation and those who want to keep Iraq strong."

There are 18 local provinces in Iraq. Until now, their authority was ambiguous. The Iraqi central government controls 99 percent of the everyday bureaucracy -- everything from picking up the trash to school administration.

This new law, which does little to clear up what roles the local and national authorities will play in those bureaucracies, does establish what the local hierarchy will look like, including the role of governors, provincial councils and other sub-groups. Some analysts say it further legitimizes the country's political process by giving the local authority more of a voice than it previously had.

"If democracy is going to be taken seriously in the Iraqi context, there has to be local representation, not just on a national level," said Eric Davis, a political science professor at Rutgers University, who often travels to Iraq. "Even though there's currently provincial governors, in effect, since there's no mechanism to channel demands upwards, it's effectively as if we had a governor of Maryland but no Maryland state Assembly. There's nothing to back him up."

Supporters of the legislation also point to the fact that by strengthening the provincial hierarchy, it weakens calls by some in Iraq to divide the country into sectarian regions. The argument goes: since the 18 provinces are divided by geography, not religious identity, the possibility of forming three autonomous "super regions" -- with the Shiites in the south, Sunnis in the center, and Kurds in the north -- becomes less likely.

"This will mean an official end to the separatist project of Iraq," Jarrar said.

Officially, the Kurds, who have the only recognized semi-autonomous region composed of three provinces in the north, are excluded from this new legislation.

According to some supporters including the White House, another benefit of the law is that it provides an opportunity for the first time to groups such as the Concerned Local Citizens -- allies of the United States that have so far been kept out of government. However, in doing so it raises the fears of some of those groups' opponents in Baghdad -- including groups aligned with Prime Minister Nouri al-Maliki -- that their parties' power will be encroached upon.

But critics of the law say it will do little to clear up the confusion of who controls what. Beyond providing an Oct. 1 deadline for local elections and prioritizing national laws, the legislation also provides the central government with the ability to sack governors and provincial councils, leading to the fear that power struggles could occur between Baghdad and local provinces.

"There's a serious lack of clarity and precision in this law," said Rend al Rahim Francke, the executive director of the Iraq Foundation and a former Iraqi ambassador to the United States. "The jurisdiction of legislation of the provincial councils is very vague. Who is allowed to pass legislation on health care, for example? The federal government or the local authority? This law doesn't say."

Jason Gluck, a legal scholar with the U.S. Institute of Peace, who served as an adviser in 2006 to Iraq's Council of Representatives on its constitutional review, said the new law also may be unconstitutional.

Iraq's Constitution says that in the event of conflict between local and federal laws, the local law takes priority. However, another section of the Constitution seems to contradict that by describing the provinces as little more than administrative units of the central government.

According to Gluck, because of the Constitution's contradictions, when the Parliament began debating the law last summer, it had to suspend discussions in order to seek an advisory opinion from the nation's Supreme Court. The court's decision leaned toward an interpretation of local authority as being broader rather than narrower.

"Every single aspect of daily life is administered by a federal ministry," Gluck said. "If local law cannot contradict national law, it doesn't give the local authorities much room to legislate."

Even supporters of the law admit to being cautiously optimistic.

"There an Arabic saying, 'It's only ink on paper,'" said Jarrar, the Iraqi consultant who supports a strong central government in Iraq. "In other words it's still a piece of paper, it hasn't been implemented yet."

Jarrar said he suspects members of the executive branch, including al-Maliki, may try to prevent provincial elections from going forward, fearing their parties will lose their grip on power. Al-Maliki's party and others in his alliance are seen to be some of the strongest supporters of decentralizing the country's power and possibly creating regional sub-states along sectarian lines.

"If the elections are fair, the outcome will be a political revolution in Iraq," Jarrar said. Groups like the Supreme Council, the leading Shiite party, could lose control in a majority of the provinces, where newer voices have emerged that haven't been incorporated into the central government, including the Sunni Concerned Local Citizen groups and similar Shiite groups.

Feisal Istrabadi, a law professor at Indiana University and a former member of the Iraqi government who helped negotiate the interim Constitution in 2003, said if the Supreme Council loses in the elections, it could be due to the Sadrists -- referring to the party of Muqtada al-Sadr, whose Mahdi Army militia is currently observing a cease-fire against American troops partly due to their expectations that new elections will come soon. "They are a much less moderate force than the Supreme Council.

"There's more than one way to short circuit democracy," Istrabadi added. "And one is to hold too many elections too soon."

-- By Robert Zeliger, NewsHour with Jim Lehrer