An orchestra director, a special education teacher and a custodian are among the handful of Cobb County school employees who, in recent years, have been given controversial polygraph tests, a unique provision allowed under the district’s discipline policy.

Cobb’s school board amended its discipline policy this summer to say employees who refuse to take the exam could be fired. The district, the state’s second largest, is the only major school district in metro Atlanta that uses polygraph tests to try to determine whether a person is lying.

Although administrators insist they rarely use polygraph tests, teacher advocates say that could change at any time and that they object to the test being used at all.

“I don’t think [polygraph tests] are reliable, dependable or accurate,” said Connie Jackson, the president of Cobb County Association of Educators. “I think [their use is] horrible and unconscionable.”

Administrators say the tests are used in “he-said-she-said” cases, such as allegations of sexual molestation or theft, where there are few witnesses.

“We use it very sparingly and only in the most serious occasions,” said Mary Finlayson, who heads the district’s professional standards and ethics office. “We have to do everything within our power to get to the truth, and the polygraph is a tool for that.”

Some Cobb residents think the tests’ use can help teachers.

“What about some of the teachers where the students lie to get a teacher fired?” said Karyn Harrison, a former South Cobb PTA member. “If it’s going to get to the truth faster, it’ll save hours of time investigating and money.”

The tests, which cost up to $150, measure breathing, blood pressure and perspiration while a person answers a list of questions.

Polygraph tests are allowed under federal law for public employees as long as they aren’t used as a sole basis to fire the person, the questions are tailored to the investigation and the employees understand that they aren’t waiving their fifth amendment rights by taking the test.

The tests are only admissible in state courts when both sides agree. The tests are largely seen as unreliable, said Steve Sadow, an Atlanta criminal defense attorney.

Several experts have questioned their accuracy and the legitimacy of examiners in recent years.

Georgia’s Professional Standards Commission rarely consider polygraph tests when considering whether to revoke a teacher’s license, said Paul Shaw, the commission’s director of educator ethics. Their office can’t afford them, and they’re often unreliable, he said.

“We just don’t see the need for them,” he said.

Since 2009, Cobb County has spent $5,100 on 25 polygraph tests conducted by Marietta-based Nix & Associates.

Of those 25 exams, 16 were used on police officers applying to be school resource officers. Fifteen of the exams showed employees were telling the truth. Five exams were inconclusive, and five found the employee to be lying, said Jay Dillon, a district spokesman.

Finlayson said employees will often change their story while taking a polygraph exam or refuse to take one.

Recently, when a counselor was accused of molesting a student, the student passed a polygraph exam and the counselor refused to take one, Finlayson said.

John Adams, the executive director of the teacher advocacy group, Educators First, and the district’s former human resources director, said polygraphs can be useful but should be used sparingly.

“The widespread use of polygraphs would likely create a fear among employees,” he said. “They should be reserved for extremely rare cases and on limited a basis.”

Jackson said teachers tell her the possibility of being tested gives them anxiety and hurts morale.

“I think it sends the message that we are being treated like criminals and that we have lost the constitutional right to be innocent until proven guilty,” she said. “Do we really want to be polygraphed anytime for anything and, if we don’t do it, we can lose our jobs?”

Morris Nix, the examiner who has conducted the majority of the polygraph exams on Cobb employees, said the tests aren’t perfect.

“But very little evidence is perfect,” he said. “It’s not voodoo. It’s not witchcraft. It’s not the Maury show. It’s a very legitimate investigative tool which is used by law enforcement agencies all over the world.”