I've been wasting time looking at some of this stuff. As someone observed, infinite, screwy variations of the facts exist in the real world. I was just reading a situation, and learned that contesting the declaration might take place significantly after the kid turns two (in some circumstances, where fraud on the nonparent signor might be one of them.) I also note that the California statute expressly states that nothing in the statute shall deprive the court of equitable authority (to do the right thing, where appropriate.)

Here's something also interesting: In attempting to improve paternity records, as a public benefit, the Legislature set up this voluntary declaration implementation scheme: Hospitals (if they have a contract with a local child agency), get paid ten bucks for each time they get the mom to sign, and have a "father" sign, a form (with lots of disclosures and fine print etc.)

In the situation I was reading, the mom said she was told she couldn't leave the hospital until she filled the form out. A name of a nice guy she knew, but with whom she had never had relations, "signed" the declaration, apparently, but the declaration failed to make it into the child agency's permanent files. The real dad, who initially said he wouldn't help pay for the kid, actually did help, and got involved with the kid for three years. But then he stopped paying. The child agency filed suit to make him keep paying. He said no, look, here's a declaration of paternity for someone else. The agency said: Look, fella, we've had genetic tests which show that you are the real father. He said: I know, that's not the point. The law says the voluntary declaration is more important than the genetic results.

I don't know how it turned out. All I know is the court of appeal told the lower court that it had better track down that declarant and find out what is going on here.