WASHINGTON — Soldiers who need special waivers to get into the Army because of bad behavior go AWOL more often and face more courts-martial. But they also get promoted faster and re-enlist at a higher rate, according to an internal military study obtained by the Associated Press.

The Army study late last year concluded that taking a chance on a well-screened applicant with a criminal, bad driving, or drug record usually pays off. And both the Army and the Marines have been bringing in more recruits with blemished records. Still, senior leaders have called for additional studies, to help determine the impact of the waivers on the Army.

“We believe that so far the return outweighs the risk,” Army Colonel Kent Miller said, who headed the team that conducted the study.

The statistics show that recruits with criminal records or other drug and alcohol issues have more discipline problems than those without records. Those recruits also are a bit more likely to drop out of the Army because of alcohol. But, those with waivers earn more medals for valor and tend to stay in the Army longer.

In a key finding, the study said that nearly one in five — or 19.5% — of the soldiers who needed waivers to join the Army failed to complete the initial term of enlistment, which could be from two to six years. That percentage is just a bit higher than the 17% washout rate for those who didn’t need a waiver to get in.