Is there a way to legally obtain someone's SSN?

1LT (Join to see) The information below might help.

http://www.identityhawk.com/Who-Can-Lawfully-Request-My-Social-Security-Number/

Not sure it's really required, unknown should suffice. Don't know what board would need your ex 14 years ago SSN. Marriage license on file at Courthouse, divorce papers, or the lawyer that filed and/or the court that issued divorce decree. Did you two ever have a joint financial account or file joint tax returns? If so, the custodian or preparer/IRS may have it on file if you don't have any copies. Car loan, mortgage, medical records or anything else is the same. Utility bills, insurance policies same. Plan B - there are websites where you can get almost anything for a fee. Read their terms to ensure it's legal and legit before shelling out $ 40-50. Was he military? That's another pathway if so. Legal aid on base? Agree that it should not be anything underhanded, to be safe. Any recruiter worth his/her salt should be willing to help you with this. Last resort - private investigator, but it will cost you and might get something started with ex. I really doubt it is actually needed.

I don't understand why the Army needs your ex-husband's SSN. I'd have the recruiter put it in writing, then ask the command if you can speak with a JAG officer.