Mechanically, Lawyer is simply a roleplaying job with no true responsibilities.
In essence, you are a glorified Passenger with a nice suit... With access to the front door of sec. This is vital to your ability to play Lawyer as it allows you to walk into Sec and interact with someone who was 'wrongfully' jailed, although your access doesn't allow you to open the cells. No, your job isn't to enforce the law, it's to make sure the law is followed. So if you intend on playing the role correct, be sure to make your best interpretation of the law and do your best to not actually get in the way of Security when they're trying to enforce it.
Still, there's a many innocent Clown batonned and cuffed, and with your limited powers(and annoyance) you can help keep the people of the station free from the horror of a cruel and unjust Sec. Be wary, this again doesn't give you the right to enforce laws, likewise the people you're to aid may also just as easily turn on you for your Sec access--A Passenger with a nice suit and any level of Sec access can pass as a Lawyer and cause havoc, so be sure to know who are your fellow Lawyers and who are just traitors pulling a cunning disguise...