[razwall]

Actually this has come up before with a similar law in Arizona, where the state tried to ban Zestimates. Volokh's analysis basically agreed with me (http://volokh.com/posts/1177792494.shtml). Though I couldn't find any info about what ultimately happened with that case.

[dtrizzle]

I'm pretty sure the Arizona legislature changed the law to make it clear that Zestimates were lawful. http://supreme.findlaw.com/legal-commentary/must-zillow-the-...

[tssva]

There was never an actual legal case. There were just cease and desist letters with threats of a case. Before any actual legal case could materialize the law in AZ was changed to allow automated appraisals without certification as long as no money changed hands for the appraisal.