Legal Question in Criminal Law in California

A little context would help. Tell us where the case is - some counties have certain letter prefixes that designate the courthouse within the county.

For example, in Orange County, a case number may be 16NF12345. That means it's a 2016 case from the North Justice Center with case number 12345

Are you sure this is a case number? It might instead be a statute your son is accused of violating. "WI" is often shorthand for the Welfare and Institutions Code, which includes some criminal statutes. But as Mr. Dane notes, different counties use different case numbering systems. It may indeed be a case number as you say.