I work with many different partners, especially when officiating younger-aged games. I cannot verify that all these partners are NFHS (state)-certified. I do not believe that it should be my responsibility. The schools, who are members of the state association (WIAA) are directed to only hire certified officials and must have two officials in order for the game to be played.
Yes, we do live in a very litigious society; however, I sincerely doubt a rationale-thinking group of people (Jury) or judge could find any certified official culpable of negligence for working with a non-certified partner, especially given the abovementioned state policies.
Of course, I am aware of some nearly unbelieveable court settlements. Anyone for some HOT coffee?