An affidavit by a person who served, posted or affixed a notice, showing such service, posting or affixing is prima facie evidence of the service, posting or affixing if the affiant is dead, mentally ill or cannot be compelled with due diligence to attend at the trial.
R 4531.Affidavit of service or posting notice by person unavailable at trial
Article 45. Evidence · Last amended 1978 · Last verified July 21, 2026
In one sentenceCPLR 4531 lets a party prove that a notice was served, posted, or affixed through the affidavit of the person who did it, treating that affidavit as prima facie evidence of service when the affiant has died, become mentally ill, or cannot be compelled with due diligence to attend the trial.
Full Text of CPLR 4531
Plain-English Summary
Process servers and the people who post notices move on, get sick, or die, sometimes years before a case reaches trial. CPLR 4531 keeps their affidavit usable even when they cannot testify in person. If a person who served, posted, or affixed a notice signed an affidavit showing that service, posting, or affixing, that affidavit is prima facie evidence of it, but only if the affiant is dead, mentally ill, or cannot be compelled with due diligence to attend the trial.
The rule is an exception grafted onto the ordinary approach to proving service, where the server typically testifies or the affidavit is admitted without much dispute. Here, the statute anticipates the specific problem of an unavailable affiant and supplies a route to admit the affidavit anyway, so long as one of the three unavailability conditions is met.
Due diligence is doing real work in the due diligence prong. It is not enough that the affiant is merely hard to reach; the proponent has to show an effort to compel attendance was made and failed, or that a similar effort would fail, before the affidavit substitutes for live testimony.
Frequently Asked Questions
When can a party use CPLR 4531 to admit a service affidavit without the server testifying?
Only when the affiant is dead, mentally ill, or cannot be compelled with due diligence to attend the trial.
What kinds of notices does CPLR 4531 cover?
Notices that were served, posted, or affixed, and the affidavit showing that act.
Does CPLR 4531 apply if the process server just moved out of state?
It can, if the party shows due diligence was used to try to compel the affiant's attendance and it was unsuccessful; mere unavailability by relocation alone may not satisfy the standard without that showing.
Is the affidavit under CPLR 4531 conclusive proof of service?
No. It is prima facie evidence, so the opposing party can still challenge whether service, posting, or affixing occurred.
How does CPLR 4531 relate to ordinary proof of service?
Ordinarily a server's affidavit of service is offered and often goes unchallenged; CPLR 4531 specifically addresses what happens when the server who signed it cannot appear at trial.
Advisory Committee Notes
This rule is the same as former § 371 with minor language changes. The phrase “where it is necessary upon the trial of an action to prove the service, posting or affixing of a notice” is omitted as unnecessary, since the affidavit will not be relevant and the evidence will be inadmissible unless its use is necessary on the trial.
Amendment History
Formerly § 4531, add, L 1962, ch 308; amd, L 1962, ch 315, § 1; L 1978, ch 550, § 7, eff July 24, 1978.
Source & verification. Provision text, History, and Advisory
Committee Notes are reproduced verbatim from the Consolidated Laws of New York.
Last verified July 21, 2026.
· Official source
Also known as: affidavit of service unavailable witnessproof of posting notice evidence New Yorkprocess server unavailable at trialprima facie evidence of service affidavitaffidavit of service deceased affiant