Legal Question in Business Law in California

A difficult question, and the answer may be different depending upon whether you are an attorney or a self-represented (non-attorney) party. Attorneys are bound by ethical standards and I would advise an attorney who has made this kind of mistaken declaration under oath to take all steps necessary to correct it, even to the extent of re-filing the case if necessary.

I did not find any case law on point.

I would note that the obligation to serve an ADR package is a county-by-county matter, and there are no state-wide requirements or specifications and, insofar as I could discover, no state-wide service requirement. Maybe one possibility would be to call on the judge who was assigned to the case during his or her office hours and ask what is ethically required.

Code of Civil Procedure section 473.5 regarding setting aside default judgments when the defendant failed to receive timely service giving actual notice in time to defend the action does not seem to apply.

Finally, it's my hunch that a lot of plaintiffs who obtained default judgments even though service was mildly defective would not bother to take corrective action and hope that the default becomes final before the defendant realizes the mistake.

There is absolutely no question that the proof of service needs to be amended. It is a statement under penalty of perjury with the court, which you realize now is false. 100% truth and accuracy is required here, whether you are a witness, a party, or an attorney.

The more difficult question is whether this would provide a basis for setting aside the default. I know of no law on point, but have not researched the issue.