Most people end up in jobs that have nothing to do with their undergraduate degree. As it turns out, lawyers also end up specializing in areas they may not have studied in law school.
As a case in point, I went down to the U.S. Bankruptcy Court for the Central District of California today, to see what I could absorb by osmosis. I also got to talk with a couple of the lawyers representing the principal secured creditor. The lead representative, who did all of the presentation during the hearing, assured me she had not studied bankruptcy in law school either, and yet she's been in bankruptcy law for about 15 years now.
So the important thing is knowing where to go to learn the law, and, of course, finding clients. Everything else should take care of itself.