Legal Question in Civil Litigation in California

Not sure which previous question you are referring to, as it could be something you read that was posted by someone else, or something you posted. Be careful about reading posts given by others, as legal advice is very factually dependent and no two situations are always the same.

It would appear that you are referring to diversity jurisdiction. Wikipedia has a good article as of this week regarding diversity jurisdiction, that explains the complete diversity rule and the amount in controversy to have a state law claim filed in Federal court. With respect to alleging domicile, that is done in the complaint. The need for verification would depend on the case you were alleging, based on any state law requirements, and verifications do not need to be notarized.

I suggest that you consult with an attorney first, before filing something in Federal court. It is easy for self represented parties to be quickly dismissed from Federal court for not following the tricky and complicated procedures.

I agree with Mr. Roach, but I want to add that diversity jurisdiction does not require that the plaintiff reside in a foreign country. Instead, it requires that no plaintiff lives in the same state as any defendant. A plaintiff need not be in a foreign country to satisfy this requirement. And even if one plaintiff is overseas, if another plaintiff lives in the same state as a defendant, the federal courts will not have diversity jurisdiction.

Note that there are other requirements for diversity jurisdiction. In particular, the amount in controversy must be more than $75,000, not including interest or court costs.