Legal Question in Civil Litigation in California

There is nothing per se improper about a lawyer sending a cease and demand to someone in another state. On the other hand, it is not automatically permitted, either. Much would depend on the state of residency for the client, where the attorney is licensed to practice, and whether the issue is one of state or federal law.

It's another matter for that lawyer to appear in a California court. A lawyer not licensed in California must receive special permission from the court before doing that.

He can probably send the letter but would either need to get a CA attorney to take action or associate wth one for pro hac vice. I would involve an attorney in the investigation to make sure there are no isses

I don't see a problem with an out-of-state lawyer sending the letter. Mr. Perry and Mr. Green are right about what it would take for her to appear in a California court (assuming she is not a member of the California bar), but if her client sues she might do so in Wisconsin. Whether that is a viable option will depend upon the facts.