> he would be entitled to request Amazon pay for the costs to produce those documents

Actually he would request that payment from California - they are the ones that hired him as an expert witness, not Amazon.

I don't know how it works in California, but in WA, the requestor pays.

Even when the requestor is the defendant? That seems open to abuse: The government sues someone, and then they have to pay huge sums just to get the documents to defend themselves.

I'm not a lawyer, but there are many ways the legal system can be weaponized.

My understanding is all evidence that can be used during trial must be turned over to the other party (barring some Perry Mason type last minute discovery that occurs during trial).

If as a defendant, you request documents, and the cost to reproduce is so "huge" as to be a burden towards justice, I imagine you could take that to a judge with a motion to compel, and have the cost amount knocked down substantially.

> separately, Amazon has named him party to a lawsuit

Is there a source for this? It seems very unlikely given the circumstances, including effect of the statute of limitations which seem to bar most plausible actions by this time...