Soon after a truck plowed through Bastille Day revelers in Nice, France, Thursday night and killed over 80 people, former Speaker of the House Newt Gingrich called for strict measures to screen Muslims in the United States.

“Let me be as blunt and direct as I can be. Western civilization is in a war. We should frankly test every person here who is of a Muslim background, and if they believe in Sharia, they should be deported,” Gingrich, who is advising presumptive Republican nominee Donald Trump's campaign, said. “Sharia is incompatible with Western civilization. Modern Muslims who have given up Sharia, glad to have them as citizens. Perfectly happy to have them next door.”

This isn’t the first time the religious belief system has been called into question in American political discourse. Here’s what you should know about Sharia law.

What Do The Words Mean? Sharia is an Arabic word that means a path to be followed (or a path to water, depending on translation) and “Sharia law” itself can refers to both a personal moral code and Islamic religious law. There are two ways to interpret the legal system, either from the Quran (interpreted by some to be the literal word of God) or the Sunnah (the tradition of the Prophet Muhammad).

Some Muslims believe that Sharia’s interpretation can be man-made and therefore up for change while others believe Sharia is divine and cannot be changed.

Who Rules On Sharia, What Are The Rules And What Are The Punishments? Sharia law was largely defined about 200 to 300 years after Muhammad’s death between the eighth and 10th centuries. The legal system — which generally covers spheres of daily life like belief, character and actions instead of actual legal issues — is interpreted by jurists and, where Sharia is the law of the land, judges.

Those spheres of life covered by Sharia can be pretty simply understood. The belief aspect says that Muslims must believe in god and other divine entities. The character section promotes humility and kindness while forbidding lying and pride. The action section includes prayer, fasting, pilgrimage, marriage and business.

There are a variety of punishments but the most violent (and the most infrequently used) are the most publicized, according to the Center on Foreign Relations. Those punishments can include flogging, stoning, amputation, exile or execution. Those are rarely used and lesser punishments are often sufficient, scholars say.

Is Sharia Compatible With American Law And Can It Be Banned? Several states have already tried to ban Sharia law since 2010, including Arizona, South Dakota, Kansas, Oklahoma, Louisiana, Tennessee and North Carolina. But, many of them have been fashioned as “foreign law bans” instead of explicitly targeting Sharia because of the concern that singling out a religion would violate the U.S. Constitution.

Supporters of the laws say they exist to ensure that constitutional liberties are not stepped on by Sharia. Opponents of the laws say they are unnecessary and discriminatory: The U.S. Constitution preempts all other laws within the borders of the country. A religious judgment that leads to a person getting stoned, for instance, would still face American court action if people violated U.S. laws.