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Smokers need not apply in one Florida county, which will soon require prospective job applicants to pass a nicotine test before starting work.

The Board of County Commissioners in Flagler County, in northeast Florida, voted last month to require potential county employees to undergo testing for nicotine use and to pledge in a signed affidavit that they will remain tobacco-free throughout their employment.

But the requirements have raised flags for a civil liberties group that said it is unconstitutional for the government to administer blanket tests for nicotine or drugs on any group of people.

The board chairman, Nate McLaughlin, told ABC News that rising health insurance costs and Flagler County's generally health-conscious outlook prompted the change. The county offers its employees weight-loss and smoking-cessation programs, and has a nutritionist and exercise physiologist available for staff.

Research has shown smokers hurt employers with lower productivity and higher health insurance. A recent study said they cost employers in the private sector an average of more than $5,800 more per year than non-smokers do.

"At the end of the day, for the taxpayers, it's a smart business decision," McLaughlin said.

Other public employers have adopted similar policies, including the county's sheriff's department, according to Joe Mayer, the county's human resources director.

"We're following our own sheriff's department, who actually beat us to the punch," Mayer told ABC News.

Testing would begin Oct. 1 for all applicants who receive a conditional job offer, and would be part of the urine drug screening that the county already conducts. If applicants test positive for nicotine, the county will not consider them for employment for one year after the screening. If a new employee violates the policy, he or she could be fired.

But the policy may run afoul of the Fourth Amendment of the U.S. Constitution, according to Baylor Johnson, a spokesman for the American Civil Liberties Union of Florida. The amendment protects against unreasonable searches and seizures.

The U.S. Supreme Court has, on a number of occasions, struck down blanket testing of public employees and public school students, citing the Fourth Amendment.

Many Florida counties have drug-testing policies that violate these judgments, and the ACLU of Florida has challenged several of those policies and a similar statewide executive order, Johnson told ABC News.

"The government can't randomly drug test entire sections of the population, whether that's state employees or people receiving government benefits, without suspicion of wrongdoing," Johnson said.

The ACLU of Florida contends Flagler County's policy of drug testing all prospective employees already violates the Constitution.

"What they've essentially done is added another possibly unconstitutional provision to an already unconstitutional policy," Johnson said.

The county's lawyers are aware of the Supreme Court ruling but still approved the policy, pointing instead to a 1995 Florida Supreme Court ruling that an applicant to a city government job had no reasonable expectation of privacy with respect to tobacco use.

"You have a responsibility to the public," Flagler County Administrator Craig Coffey told ABC News. "It'd be no different than doing a credit check on people handling money. … In this case, it's a tobacco check."