Many lawyers take a belt-and-suspenders approach to clauses that are intended to transfer copyright ownership from the developer-vendor to the customer with respect to the customer’s deliverables it is paying for, when representing the customer. “Let’s call it an assignment,” they say, and “let’s also call it a work for hire, just in case.”
The problem here is that in certain circumstances, it can be crucial to know with objective certainty whether copyright has been assigned, or whether ownership of it passed automatically via work-for-hire doctrine under applicable copyright law (such as the US Copyright Act’s definition of work made for hire in section 101).
If the former, post-termination rights may apply, giving the party assigning copyright the right to rescind the assignment and take it back for free (albeit only after a considerably long period of time). If the latter, the transfer of ownership is automatic and cannot be rescinded.
That said, it’s not always clear whether work for hire rules will apply. The key is preserving the transfer of title in a way that best protects the customer.
Solutions to this problem can be found here at Redline.