That is a thought-provoking perspective, although the answer isn't straightforward (like most everything appraisal-related). Although I provide reference either to published documents or conversations with the jurisdictional authority (date of communications & initials of rep), I have never cited a court case, based upon the response I received from the AF a few years ago when I asked whether peers routinely do so, because I vaguely recall that nobody who responded did so in the affirmative. More about your perspective would be appreciated (although I started the day at 3 am to make tangible progress on specific assignments rather than to speak about appraisal theory, although it would be great to attend Appraisal University if such a place exists...)
I can see why standard lending appraisal practice wouldn't be qualified to opine on certain items related to legal implications in real estate. In my practice area I am qualified to opine on certain land use regulations, tax regulations, and their market reaction as applicable to the subject property and comparables, market, or valuation related items.
This didn't happen from an appraisal university, it was from training and practicing in the legal support side and taking department of transportation courses which are based on constitutional law.
Directly to your question. You have two issues, first is that you lack the database to research the item the client needs in the appraisal analysis. The second is that even if you had the database (legal statute or case law) it might be so complex you might not have the skills to opine on the application of the legal framework to the market reaction and how that affects the subject.
The first part is to bring in a specialist, probably an attorney if it is really complex, to opine on the rebuild. Then perhaps default to a specialist such as myself for the market reaction to the condition upon the subject property.
You shouldn't have to get up at 3am for this profession, attorneys don't start work that early and neither does the zoning department. You will be too tired by 5pm to take the calls from the clients that pay well and value your skillset. I only know of shift workers and roofers in the south that start work that early because they have to and the roof is too hot by noon.