Legal wording

I was noticing legal wording the other day, and it seems that lawyers go way out of their way to never use the possesive when refering to plaintiff or defendant. Is that a legal faux pax, to use Plaintiff’s or Defendant’s, is one to instead reword to be able to say simply Plaintiff or Defendant?

Perhaps the possessive form is considered too informal by some? But I’ve seen plenty of judgements where the possessive forms are used.