Briarwood Presbyterian Church in Birmingham, Ala., wants to add a service offering no other U.S. church has:  Its own police force.

With 4,000-plus members, two private schools and its own radio station, this megachurch's leaders asked state legislators for permission to set up a private law enforcement department to monitor its assets. The bill comes at a time when American places of worship are increasing security, but a church-only police force raises constitutional questions that are ripe for a legal challenge, reports The Associated Press.

The bill regarding the proposed police force was introduced by Republican Rep. Arnold Mooney, whose wife and daughter work at Briarwood Christian School. All three of his children graduated from Briarwood schools.

Opponents to the concept worry true crimes on the church's campus could be covered up by the church, and there are doubts about how closely any church police group would work with neighboring police or to whom they ultimately would answer.

Experts say a church with its own police department would be unprecedented in the U.S.

Heath Grant, assistant professor at John Jay College of Criminal Justice in New York City, said, "From the perspective of security, churches usually have relationships with the local police departments. I don't know why that wouldn't be sufficient."

The church's managers reportedly already hire off-duty police officers from nearby jurisdictions to cover its events, but they claim there often are not enough officers available to help. Church officials also have indicated they worry about mass shootings.

AP indicted that 21 of Mooney's colleagues in the Republican-controlled House support his bill, which passed the Legislature last year but was not signed into law by Gov. Robert Bentley. Debate in the House is expected before the session ends in May.

Richard Levy, a constitutional law professor at Kansas University, said such a move would be the church take the role of the government "I would expect that if the law is enacted it would not be very long before it is challenged."

The bill was first proposed after students at Briarwood's high school were arrested in a drug bust in early 2015, which made a splash in Birmingham-area media, reports AP. While church administrators deny the raid prompted this bill, critics worry that similar instances could go unreported if the church had its own police.

Church representative communicated they intended for the police department to be like those at colleges and universities. It would not have a jail or dispatch center, and would cooperate with surrounding police forces if someone needs to be detained, according to documents church administrator Matt Moore provided to AP.

"The sole purpose of this proposed legislation is to provide a safe environment for the church, its members, students and guests," the church said in a statement.

Church police officers would be trained to state policing standards and have all the duties and powers as other law enforcers, but they would be confined to the church's grounds and the church's secondary school in nearby Shelby County.

The bill would allow Briarwood to hire as many officers as it wants.

Co-sponsor Republican Rep. Allen Treadaway, a Birmingham police captain, said if a wealthy church can attract and retain officers, let it do so.