[walter biscardi] “The Project Files are your artistic work for which you are being paid.”
I might suggest that for many producers the raw footage is also their artistic work, which is perhaps where the issue arises. Clearly there can be circumstances where all footage must and should belong to the client (best reflected in contract) and circumstances where it will be more the work and under the ownership and control of the producer (again, best reflected in contract.)
Even though the producer in law probably normally owns the raw footage, clearly the client has an implied right to the use of that footage in their project, and common sense and courtesy would indicate care in any planned alternate or additional use of the footage – it could clearly cause a great deal of upset to a client in some circumstances.
But circumstances will vary. If a client pays for a sequence to be designed, constructed and filmed, reuse of that footage would seem problematic. But suppose the client pays for a few shots in a location that you see a use for in multiple projects; you undertake a lengthier filming trip (quite possibly not loading all costs into one project) and film far more material than you could ever use in the one project. Why, then, would you want to see all of that footage, – physical material and rights to use – transfer to one client …?