The number of people with criminal records in the United States military has doubled in the past three years, according to a new study.
The US army says it will recruit quality young men and women
The report comes at the same time as the US armed forces is facing a decline in the number of volunteers wishing to enlist in the armed forces.
It says 824 felons were allowed to sign up in 2004 as opposed to 1,605 in 2006 under the moral waivers scheme.
Almost 59,000 drug abusers entered the military in the same period.
The report, sponsored by the American think tank Michael D Palm Centre, also showed that 43,977 people convicted of serious misdemeanours such as assault were permitted to enlist.
The moral waivers programme allows otherwise unqualified candidates to serve in the military.
With the continuing wars in Iraq and Afghanistan, the US military has raised its age limit for recruits from 35 to 42, and accepts more people with lower scores on its aptitude test.
The report's author, Michael Boucai, said the problem was not that the Armed Forces were letting in ex-offenders.
"Most of these recruits become fine service members, and military service often has a strong rehabilitative effect," he said.
"The real problem is that, increasingly, the military fails to recruit the best and the brightest."
The director of the Michael D Palm Centre, Aaron Belkin, said in all about 100,000 people with what he called troubled pasts had joined the military over the past three years.
He said it showed the problem the US had "meeting our military needs in this time of war".
A US army spokesman, Paul Boyce, told the Associated Press "anything that is considered a risk or a serious infraction of the law is given the highest level of review."
"Our goal is to make certain that we recruit quality young men and women who can keep America defended against its enemies," he said.