WASHINGTON — The Air Force said Tuesday it was awaiting a legal opinion from the Defense Department’s top lawyer on whether an enlisted airman who’s an atheist can opt out of the phrase “so help me God” in his re-enlistment oath.

The airman, stationed at Creech Air Force Base in Nevada, was told in late August that federal law requires those words in the enlistment oath, attorney Monica Miller of the American Humanist Society said. Air Force policy previously allowed airmen to drop the phrase if they wished, but the policy was changed in 2013.

“The opinion that we’re seeking will help inform future decisions and the latitude that can be taken with the oath,” Air Force spokeswoman Rose Richeson said Tuesday. “But the Air Force has to comply with law.”

But Miller said the Air Force must move quickly to follow what she said are clearly-established legal requirements. The airman, who has chosen to remain anonymous, is scheduled to leave the Air Force in November if he doesn’t reenlist.

“We still have not received a response,” she said Wednesday. “However, I informed the officials yesterday that if they don’t take corrective action by September 19th, we will have no choice but to bring this matter to court.”

The airman’s right to modify the oath to fit his lack of religious belief is not in question outside the Air Force, a defense official who discussed the matter on the condition of anonymity said Tuesday.

“I’ll tell you that there is no legal requirement to say ‘So help me God’ in any federal oath/affirmation by a person taking the oath,” the official, who was not authorized to speak publicly about the matter, said in an email. “That is, saying ‘So help me God’ in any federal oath is optional at the discretion of the person taking the oath (not the person administering the oath).”

A host of Supreme Court and lower court cases support the airman’s right to opt out of calling on a deity, as does as the text of the U.S. Constitution itself, said military legal expert Eugene Fidell, who teaches military law at Yale University.

According to Article VI of the Constitution, federal officers “shall be bound by Oath or Affirmation, to support this Constitution; but no religious Test shall ever be required as a Qualification to any Office or public Trust under the United States.”

But, Fidell said, a religious test is what a requirement to say “so help me God” amounts to.

carroll.chris@stripes.com

Twitter: @ChrisCarroll_

