There are three types of people in this world: those who don't care about Oxford commas, those who think they're useless and those who will get really mad when they read this sentence. Regardless of which camp you're in, one thing is clear: comma placement can vastly change the meaning of a sentence. When it comes to the law, as one U.S. Circuit judge proved, that's really important.
Related: Punctuation With A Double Punch