Recruiters consider an individual's criminal record when deciding who's in and who's not. Minor traffic offenses won't keep you from joining the military. However, an array of other charges might disqualify you, and other charges will automatically disqualify you.
Minor Non-Traffic Offenses
Potential recruits who have five or more minor, non-traffic offenses on their record are disqualified from joining the military unless they can obtain a moral waiver. This is a very wide category of offenses that includes failure to appear, being drunk in public, littering, minor vandalism, possession or purchase of alcohol or tobacco by or for a minor, indecent exposure, harassment and stalking.
Level-300 Misconduct Offenses
Recruits can obtain moral waivers for domestic abuse charges but are disqualified from joining if they are not granted one. More than one instance of solicitation of prostitution or being caught with a prostitute is an automatic disqualification, as are more than two DUI charges or charges of marijuana or paraphernalia possession. Six or more of any 300-level offenses -- including assault, criminal trespassing, resisting arrest or leaving the scene of an accident -- disqualify a recruit.
400-Level Major Misconduct Offenses
Recruits with one 400-level offense are disqualified from joining, unless they are able to obtain a waiver. More than one major misconduct offense is an automatic disqualification. These include such major crimes as aggravated assault, selling drugs, grand theft auto, kidnapping, hate crimes, burglary, child sexual abuse, possession of child pornography, manslaughter and murder.