Proving proof of service by mail is false

The other party claims they served me, but I never got it. How do I prove the other party’s server lied in their Proof of Service?

First, make sure to look everywhere it might be and ask anyone else who picks up your mail if they might have seen it, just to make sure.

Next, get a copy of the Proof of Service from the court file, and check that it is completely filled out, that the person who mailed it was not a party, that all the information makes sense (dates match, etc.) and that the mailing address they used is the one you use on your court paperwork. Any of those things could be a basis to challenge the service.

Finally, you can schedule a motion for relief from the negative consequences of the false service (such as not being able to respect to a motion that you then lost). You can call the person who signed the proof of service as a witness and question them about their claim that they mailed it.