The logic of statistics is useful in developing legal arguments, and the methods of statistics are often directly applicable to data pertinent to a case. It's the same thing you're trying to do in law, or any time you try to convince someone of something through logical argument. The main difference between law and statistics is that law works with more inexact things, like uncertain evidence, or words. The words in the law have special legal definitions, and you have to plug those definitions into the words in the law and trace them through to work out what the law means. Words and their definitions become like variables and the functions that relate variables to each other, and language becomes like mathematics and statistics.
Statistics can also come up occasionally in more direct ways.
Suspects are now identified with DNA evidence, which depends not just on biology and genetics but also statistics. Matching DNA sequences is not always quite as exact as people think, and some interesting statistical issues can come up in unusual cases. I personally have used statistics in trying to challenge the reliability of drug testing results. My old statistics professor gave me the idea. I often say there's nothing I'd rather be than a public defender.