Plaintiff is the master of their complaint, and can write whatever they want.
However, a code pleading (aka "fact") jurisdiction requires that the plaintiff allege ultimate facts which if proved at trial would cause the court to enter judgment for plaintiff.
Ultimate facts are those facts which satisfy the elements of the cause of action. They do not include statements of law, whether statute or case law.
A plaintiff and/or counsel may cite case law or statute as a means of informing the court as to what elements are necessary to satisfy the cause of action, and then state the allegations. However, no citation to legal authority is necessary to make a code pleading. It's up to the defendant to demurrer, if the plaintiff fails to state a claim for which relief may be granted -- and for the judge to research the law to ensure that any dismissal or demurrer is sustained based upon applicable law.
Concerning a 9th Circuit ruling, in California such federal court
rulings are persuasive but not binding authority -- unless the issue concerns a matter of federal rather than state law. So, as a general rule, citing a 9th Circuit ruling as a means of providing the elements of a case is not generally advised, unless you are certain that the ruling is followed by the California state courts.
Hope this helps.