They made a movie about this. I think it was called “the Dirty Dozen”.
A great idea. But only for the lifers who have nothing to loose. They could be used for really dangerous operations- like going after the guys responsible for the current financial crisis.
Why not?

The Military is a place for Honorable Men & Women not felons.

The reason is because ex-cons have morality issues. Most of us are brought up with a loving mom and dad in their childhood, which teaches them morale responsibilities. Most ex-cons had lived dysfunctional childhood, which manifested into criminal behavior as they got older. In the 2nd World War, when high attrition rates (soldiers killed) forced the military to lower their standards, a lot of men with criminal past refused to obey orders. Remember the movie, the Dirty Dozen ?? These men proved incorrigible, and reports came that some had raped women and children when they were behind enemy lines, where there’s only your own morale conviction to guide you between right and wrong. It was the same during the Civil War, where any man was allowed to sign up. Men who were fugitives, fleeing for committing bank robbery or murder, had enlisted into the military to hide from posse who were looking for them.

Edit ►In response to the thumbs down, and what Celia H posted, I’d like to elaborate further on why it’s a very bad idea to let men with questionable moral issues to serve in the military. In the movie “Band of Brothers” and “Letters from Iwo Jima,” there are scenes where American soldiers shot PWs (prisoners of war) who were unarmed. These are NOT fictional. Besides committing atrocities of rape on civilian women and children, and refusing to obey orders from their COs (commanding officer), they often refuse to take prisoners. When there are no ranking officer, men with violent criminal past will shoot and kill enemy combatants who are wishing to surrender. The Army and Marines had noticed a pattern; all complaints of soldiers who shot and killed unarmed PWs often involved men with serious criminal convictions before they entered the military.

The movie “Band of Brothers” was based on personal journals, letters, and interviews with men who served in WW2. There was a scene where a German soldier came upon 2 Americans helping a wounded comrade. The German soldier looked over his shoulder to make sure other Germans were not near, then lowered his rifle to help the Americans. He gave his personal vehicle over to the Americans to help them escape. This REALLY HAPPENED !! This was written on a journal by the soldier who was wounded in that scene. When he saw the German soldier with his 8mm Mauser trained on them, he knew he was on his way to a PW camp. As the German soldier helped them to escape, he noticed he was wearing a crucifix, implying the German soldier acted out of religious moral convictions. This was not shown in the movie. In contrast, men with serious criminal convictions would not hesitate to open fire on unarmed, or disadvantaged combatants. When you have the drop advantage on an enemy, the rules of engagement clearly says you must give your enemy the opportunity to surrender. Men with questionable moral standards would not hesitate to fire on combatants with their hands up in the air, who wish to surrender.

If we allow men with violent criminal convictions into the military, we would begin to receive reports of soldiers committing atrocities behind enemy lines. The US Army and Marines would begin to have the same reputation as the SS Division of the Nazi Germans. To avoid this, we would need to stipulate, men with criminal convictions CANNNOT participate in ground combat. They can serve as cooks, drive trucks to resupply the front lines, or other non-combat support roles. Trusting them to abide by rules of conduct in war, is like trusting the fox to guard the chickens against predators.

As a prisoner you are not part of society and you have been locked away from it. Being in Military is being part of society.

Historically, in the USA and elsewhere, recruiting prisoners has been a time honoured way of filling military ranks in times of shortage. In WW1 many prisoners were recruited into the army, and even during Vietnam it wasn’t unusual for young men convicted of crimes being given a choice between prison and joining the army.

I mean, if we are planning on releasing a prisoner eventually, why not let him repay his/her debt to society doing something productive instead of sitting in a cell?

Short answer: If the war is just, it’s a great idea. Countries that have been invaded have often given rifles to everyone in prison and sent them to the front lines, wouldn’t you?

I doubt any ex-Serviceperson will agree with this suggestion – certainly I would not have wanted to serve with, or command, anyone that could not be trusted; and criminals, by definition, cannot be trusted.

Minor convictions are often not a bar to recruitment, especially if they are a result of a youthful mistake or foolishness, but minor convictions don’t usually result in imprisonment for a first offence.

Then, consider what soldiers in particular learn – should we teach fieldcraft and escape and evasion to thieves, or close combat to thugs?

Ignore the films and fiction – they are for the entertainment of those who don’t know.

Military has enough discipline problems without adding a bunch of criminals to the mix.

Criminals do not make good soldiers. There are real ethics and leadership issues that make people disposed to committing crimes very poor material for recruiting.

I have a feeling that a lot of prisoners begin to harbor a hate for the government/the system/the “man”/etc after being locked up long enough. Maybe they believe that they will turn against the military, or use the information they learn in the military for bad things when they’re done their tour.

I’m all for us using prisoners in the military. A lot of them know how to use weapons, are used to wearing a uniform, discipline, bad food, sleeping in confined bunks with other smelly men. Sounds like they would fit right in. They could get a choice: twenty years in prison or 5 years in Iraq. I think they would take the 5.