[pogo101]

I disagree that it'd be a legal mess. It would be common knowledge in Arizona that, prior to X date, it was in the 9th Circuit. Look, this isn't really even a debatable point, in my view: the fact that a state's lawyers have to learn, on their first day of practice, that there is this minor issue with the Circuit membership of their state, isn't a "legal mess."

[aristeides]

So either a bunch of precedents in states like Arizona suddenly lose their force, or there are different precedents for different states within a circuit. (And what would this say about the legal validity and legal consequences of prior decisions by, say, federal district courts within Arizona following Ninth Circuit precedents?) Either is highly undesirable. Predictability of result is one of the most important factors in the law.