An applicant to the US Navy cannot enlist if they have been arrested for certain criminal offenses (a conviction is not necessarily required) unless a "waiver" is obtained. For some offenses a waiver can be obtained; for others they cannot. Without knowing exactly the details of your son's offense it is hard to say for sure. What you and he need to do now is to speak with a criminal law attorney. They can research theapplicable military regulations and advise your son as to best proceed with his case. Hire a lawyer in the area of where the court situated. An experienced attorney can us their local contacts to your sons best advantage.