Substituted service is a legally appropriate way to serve a summons and complaint. Did you receive it? I don't know what the proof of service says in regards to their attempts to serve you. If you got the paperwork, why are you contesting service? It sounds like the judge will just allow him to serve you again. Did you really now know about the default hearing or did you ignore it? This really sounds more like a homework assignment. Rutter and the annotated code of civil procedure have cases and practice pointers as to how to proceed if you want to file your motion. If it's baseless, the judge will remember it and not like it.
The authority for substituted service is provided under California Code of Civil Procedure section 415.20(2):
"If a copy of the summons and of the complaint cannot with reasonable diligence be personally delivered to the person to be served as specified in Section 416.60, 416.70, 416.80, or 416.90, a summons may be served by leaving a copy of the summons and of the complaint at such person's dwelling house, usual place of abode, usual place of business, or usual mailing address other than a United States Postal Service post office box, in the presence of a competent member of the household or a person apparently in charge of his or her office, place of business, or usual mailing address other than a United States Postal Service post office box, at least 18 years of age, who shall be informed of the contents thereof, and by thereafter mailing a copy of the summons and of the complaint (by first-class mail, postage prepaid) to the person to be served at the place where a copy of the summons and of the complaint were left. Service of a summons in this manner is deemed complete on the 10th day after the mailing."
If you are arguing that substituted services was improper, you need to allege specific facts in your declaration. If you are trying to vacate a default judgment, you need to set forth the facts in your declaration about how you first learned of the judgment. The court is going to focus not so much on the specific compliance with CCP 415.20 because there is a presumption that the process server's proof of service is valid, but rather on the facts which caused you not to be able to timely respond to the summons and complaint.
Frank W. Chen has been licensed to practice law in California since 1988. The information presented here is general in nature and is not intended, nor should be construed, as legal advice for a particular case. This posting does not create any attorney-client relationship with the author. For specific advice about your particular situation, consult with your own attorney.