Many young men and women who want to serve their country might not realize how high the standards are. In addition to physical and medical standards, the military has specific expectations for behavior. An applicant who has a history of substance abuse or criminal activity, for example, could be disqualified either temporarily or permanently.

Medical Issues

Disqualifications regarding physical fitness are sometimes enough to completely prevent someone from entering service, but not always. They do throw up red flags for recruiting offices, but some issues can be worked around or improved. Some medical disqualifications include a history of gastrointestinal disorders, blood disorders such as anemia and dental disease which might prevent normal service. Applicants must also pass minimum standards of physical ability, such as joint movement, hearing and sight that corrects to minimum standards. Any other deformities or diseases that could put troops at risk or cause the applicant to be unable to perform her duties may also be cause for disqualification. Each branch of the military also has its own height and weight requirements. For instance, a man between the ages of 17 and 20, who is 6 feet tall, must weigh no more than 200 pounds.

Legal Disqualifications

The military is interested in taking on applicants who adhere to strict moral standards. One way of screening this qualification is to look at an applicant's legal history and any trouble he might have run into with the law. Not all criminal activity is immediately disqualifying, though some is. Some will require a waiver, meaning the branch of the military the applicant is applying for will have to examine the specific incident and make a separate decision on whether to make an exception. A financial background check will also be performed. Sometimes a history of debt will be a disqualifier, as starting military salaries will likely not be enough to help a person overcome a significant amount of debt. Convictions for DUI would require a waiver in order for the applicant to proceed.

Alcohol and Drugs

A drug test is administered on all applicants for military service. A positive test will result in rejection, but will come with the option to retake the test in six months. No waiver can get an applicant through on a positive test, and a waiver may be required on a negative test if the applicant has tested positive before. Applicants may also be disqualified for previous arrest records relating to drug or alcohol abuse or admitting to having dependence issues on either drugs or alcohol.