The decision by a swath of northern, predominantly Muslim states in Nigeria to adopt a hard-line interpretation of Islamic law in 2000 has sparked sporadic clashes among residents and posed some problems for the government.

For followers of Islam, many edicts of morality and lifestyle are found in the body of Islamic law known as "Sharia" -- a set of religious rules that are observed in various ways around the Islamic world. Some states adhere strictly to codes of conduct outlined in the Quran while other more moderate nations have attempted to include aspects of Islamic law in more secular forms of governance.

What is Sharia law?
The word Sharia means "the path to a watering hole" but is often translated as "the way" or "the path." It offers guidelines for everyday life, including prayers and donations to the poor. As addressed in the Quran, Sharia prescribes modest dress for both men and women and has been interpreted to require single-sex schools and transportation.

Several factors determine the underpinnings of Islamic law. The Quran (the Islamic holy text), the Sunna (the prophet Mohammed's teachings) and Muslim scholars' legal rulings all contribute to the collective body of Sharia laws.

At its broadest meaning, Sharia includes two major components -- rules governing acts of worship, or al-ibadat, and laws covering human interaction, or al-mu'amalat.

It is this second branch that has caused the most political turmoil. The laws contain violations known as "Hadd" offenses, which include sexual intercourse outside of marriage, alcohol consumption, highway robbery, theft and murder.

Sexual offenses can carry a sentence of stoning to death or flogging. Theft can be punished by the loss of a hand.

Since Sharia is interpreted and practiced in different forms around the world, not all predominantly Islamic societies implement such penalties for committing a Hadd offense.

Like several Middle Eastern countries, Egypt recognizes Sharia as part of its jurisprudence but chooses not to enforce severe Hadd penalties as part of state law. Instead, adultery is often punished with short prison sentences.

Parts of Sudan, Saudi Arabia, Pakistan and Iran are all known to have adopted the Sharia punishment code, but still enforce penalties with varying levels of consistency. Despite the toppling of the Taliban in Afghanistan in 2001, the new Afghan parliament adopted relatively hard-line Sharia laws and at one point attempted to execute a man who had converted to Christianity, forcing him to flee to Italy.

Iran is one of the few countries known to have carried out death by stoning sentences. In other countries, these sentences are often commuted to lashings or prison terms.

Islamic law in Nigeria
For centuries before Muslim leaders in Nigeria adopted Sharia law as part of their state-run legal system, Islamic code was practiced in the area that would become northern Nigeria.

When the region came under British rule in the early 1900s, the British allowed the use of Sharia, but did not permit the enforcement of amputations or executions as punishments.

After the country gained independence, Nigerian leaders relied predominately on establishing secular courts and suppressed the use of Sharia penalties, fearing they would inflame tensions between Muslims in the north and Christians in the south.

Although Christians are not subject to Sharia law, its use has created an atmosphere of unease and intimidation between religious groups, often leading to violence.

Nigerian attorney Muzzammil Sani Hanga told the PBS program Frontline in 2001 that corruption and crime contributed to the re-emergence of the Sharia penal code in certain states.

"I believe the clamor for the implementation of Sharia is like an open show of defiance against the government, which is perceived by the Muslims as the sole agent of corruption in this country, "he said.

Nigerian leaders also have drawn a distinction between those who may use Sharia for political gains and those who want to observe the Islamic law solely for religious reasons.

"The genuine Sharia, Islamic Sharia, is part of the religion and is part of the way of life of a Muslim and part of the way of life of Nigerians," Nigerian President Olusegun Obasanjo told the news service allAfrica.com in 2001.

"It is what I call political Sharia that is new and that will come and go, because if you want to use Sharia to achieve political ends it will not hold. It may stick for a while, but it will not hold," he said.

Sharia implementation continues to raise difficult questions in Nigeria and around the Muslim world on how to separate the secular and religious systems.

Nigeria's population "encompasses more Muslims than the population of any Arab country, including Egypt," African studies scholar Ali Mazrui told a conference sponsored by the Nigeria Muslim Forum in 2001. "But can the Sharia be implemented at the state level without compromising secularism at the federal level?"

Obasanjo's Sharia problems
Nigeria's Sharia law simmered as an internal dispute until 2002 when Amina Lawal, a 30-year-old divorced Muslim woman who had a child out of wedlock, faced charges of adultery in a Sharia court.

Lawal was convicted in March 2002, and a Sharia court sentenced her to death by stoning at Bakori in northern Nigeria's Katsina state.

Lawal's sentence and others like it have triggered outrage from human rights groups opposed to the death penalty and physical punishments.

Obasanjo said if Lawal's case reached the Supreme Court, he would make sure it was overturned, a move that could have prompted widespread protests among Muslims in the north.

The public outrage and international pressure mounted ahead of her appeal and when the Sharia court heard her arguments in September 2003, the court overturned her death sentence, saying authorities had not allowed her to adequately defend herself in the original trial.

"The law of justice has prevailed over the law of man. Amina is free to go, to do what she wants," Lawal's lawyer, Hauwa Ibrahim, said at the time.

Since the decision, Nigerian court officials have carefully treaded the line between religious law and the national court system and many of the differences between the two systems have quieted.

-- Updated by Lee Banville for the Online NewsHour