Legal Question in Appeals and Writs in California

Unless the California Supreme Court issues the writ of mandamus there is nothing to prohibit the Court of Appeal from determining the matter before it. It would be highly unusual for the Supreme Court to take any action since it has reviewing power over any action by a lower tribunal.

Unless the Supreme Court granted the stay prior to the decision by the Court of Appeal, you have no basis for a motion to vacate the Court of Appeal's decision. A motion to vacate would almost surely be summarily denied, and your petition before the Supreme Court is now moot. It appears your only remedy is an appropriate petition for writ of certiorari before the Supreme Court.

You did not get a stay just by asking for one. Since the Supreme Court did not issue a stay order, there was no stay for the Court of Appeal to violate.

Offhand, it's not clear to me that the Supreme Court can order a Court of Appeal to stay a case that has been submitted. Even assuming that it can, it would only do so in extraordinary circumstances. Nothing you have written suggests that there was good reason for it to issue a stay.

I disagree with Mr. Perry as to your remedy. If you disagree with a decision of the Court of Appeal, you need to timely file a petition for review to the California Supreme Court, not a petition for a writ of certiorari.