There are opportunities are Captains, including rated folks, to go to law school via either FLEP (Funded Legal Education Program) or ELP (Excess Leave Program). The AFI describing the programs and requirements is 51-101. The number of FLEP selects was 6 in 2013, 0 in 2012, and 1 in 2011. The number of ELP selects was 2 in 2013, 2012, and 2011. The program eligibility requirements further limit the opportunities for rated folks to cross-over.
FLEP pays you your active duty pay and pays for law school. For FLEP, you must be an O-3 with 2 to 6 years TAFMS before law school begins. If rated, you must have served 3 years from the date you completed training before law school begins. In general, that leaves only one chance to apply for FLEP. June 2009 Grad USAFA/ROTC; Jan 2011 Grad UPT; Jan 2014 Eligible for FLEP; Aug 2014 Law School Starts; June 2015 6 year TAFMSD so ineligible for Aug 2015 law school. In addition, your UPT ADSC does not continue running during law school, so the above example person would have an ADSC until Jan 2024. You also must request a permanent disqualification from aviation service, effective the first day of law school.
ELP allows you to stay on active duty, but you serve without pay, except during summer internships. Using the Post-911 GI Bill would buffer the pain in the wallet. For ELP, you must be an O-3 with 2 to 10 years TAFMS. Your functional must release you to ELP, which I know in some airframes is not going to happen.