In addition to the matters required to be set forth in the affidavit by the plaintiff for publication of summons, it shall appear by the affidavit that the plaintiff used reasonable diligence to ascertain the identity and residence of the unknown defendants and of any persons sued as heirs and devisees.
§ 801.9.Reasonable Diligence to Ascertain Identity and Addresses of Unknown Defendants to Appear In Affidavit
Title 10. Actions In Particular Cases · Chapter 4.6. Actions Concerning Real Property Titles Affected by Public Improvement Assessments · Last amended 1969 · Last verified July 28, 2026
In one sentenceSection 801.9 requires the plaintiff's affidavit supporting publication of summons to show that reasonable diligence was used to identify and locate the unknown defendants and any persons sued as heirs and devisees.
Full Text of § 801.9
Plain-English Summary
Publication is a substitute for real notice, so the law demands proof that the plaintiff tried in good faith to find the people being published against. Beyond whatever an ordinary publication affidavit already has to show, this section adds a specific requirement for this chapter's actions.
The affidavit has to demonstrate that the plaintiff used reasonable diligence to ascertain the identity and residence of the unknown defendants, and of anyone sued as an heir or devisee of a deceased claimant under § 801.3. That diligence requirement is what justifies treating publication as adequate notice for the unknown defendants bound under § 801.10.
Frequently Asked Questions
What must the plaintiff's affidavit show beyond the usual publication requirements?
That the plaintiff used reasonable diligence to ascertain the identity and residence of the unknown defendants and any persons sued as heirs and devisees.
Why does this diligence requirement matter?
It's what justifies binding unknown defendants through publication rather than personal service, since publication substitutes for real notice only when real efforts to find those people came up short.
Amendment History
Amended by Stats. 1969, Ch. 1611.
Source & verification. Section text is reproduced verbatim from
the Deering's California Codes Annotated / vLex. Enacted by the California Legislature.
Last verified July 28, 2026.
· Official source
Also known as: reasonable diligence affidavit californiapublication of summons diligence california