Legal Question in Family Law in North Carolina

Depends. It may not be fraud at all. Fraud requires intent. If the divorce was granted through mistake then no fraud was committed however the divorce could be set aside. Normally, both parties to the divorce are in on the fraud and basically lied to the Court about the separation date in order to avoid the one year separation period. This is likely fraud and perjury for the Plaintiff and just fraud for the Defendant. As you call it, fraud "on" the Court. However, if the Court and by Court, I mean the Judge, knew the separation date was incorrect and allowed the divorce to be granted anyway it would likely be fraud "by" the Curt as well.