Sounds like you really want to go to law school rather than business school, but you want to use the MBA to leverage and give yourself a leg up to get into a better law school because of your GPA.
The law school admissions process appears to be more numbers driven than business schools because if you see some of the grids from LSAC's guide to law schools, certain numbers practically guarantee admission, and others do not. It is also clear that low GPA's for law school (3.3 and below) make it nearly impossible to get into Top 40 law schools, much less the coveted "T-14" tier:
Yale, Harvard, Stanford, NYU, Columbia, Chicago, UVA, Berkeley, Michigan, Penn, Duke, Northwestern, Cornell, Georgetown
, unless you score close to 170 (top 3%ile on the LSAT) for the schools around the Top 40, and definitely above that for the schools I listed above. Granted, law school is having some tough times right now getting students due to the scamblogs, and the general climate around big law firms (right now, NY firm Dewey and LeBouef is basically about to go under). However, I don't anticipate seeing the standards drop that much if at all for the T-14 schools, and marginally for most of the rest of the Top 40.
With B Schools, especially full time, your numbers will earn you an interview, but after that you still have to sell yourself more.
Even LOR's may have to be different. Business school wants only professional letters. Law schools want your professors, unless you are at least five years out of college and you're about there now, so they'd accept your boss' rec too.
And with undergrad grades, well, you're farther out than most law applicants presumably so grades may not count so much, but they still will count heavily, and you aren't necessarily getting to a better school because of work experience.
If you do a JD/MBA, you are going to have to apply to both schools in order to do such a program, but what side of the degree do you want more, and if you only had to pick one degree, what would it be?
Hope this helps. Good luck!