I believe that's an ABA rule, actually, that full-time 1Ls can't work more than 20 hours per week. At my school, I think we're supposed to get permission if we work more than 10. I *think*.
Anyway, I mooched off my husband/loans mostly, but I did actually do some contract work on weekends during second semester. It was pretty taxing, but it's doable if you are smart about time management.