@Vincenzo -- I think most people get involved in criminal law because it is (arguably) easier than some more complex branches of civil law.
What I mean by that is that the criminal code is pretty clear in terms of what elements are necessary for each crime. The state can either prove those elements or it cannot. The defenses job is to throw enough reasonable doubt on a case to make sure his or her client walks free.
Compare that to, say, a divorce. That is all mired in ill defined laws and precedents that it is difficult to bring a client through that process.