It's a complicated subject. By law, you can not be compelled to create a document that didn't exist, but you can be compelled to produce a copy of the document

It's a complicated subject. By law, you can not be compelled to create a document that didn't exist, but you can be compelled to produce a copy of the document that does exist. It becomes murky when you consider that IP addresses etc do enter the memory of the computer before being discarded, and thus can be argued to have temporarily formed a document. There was at least one court case where a judge felt this was enough to say "you have the document, you must make a copy at my request". I don't remember the details of the case, and don't remember how it ended. I hope that sanity prevailed and the "thou can not be compelled to create a document" policy was reinterpreted in a more reasonable manner.