This marks one of the not-so-subtle attempts to disguise what the WFH aspect of US copyright law is really doing. The critical language that makes this clear is not in the definition of a work made for hire (or work for hire, or WFH), but buried in the middles of the statute.
§ 201(b) In the case of a work made for hire, the employer or other person for whom the work was prepared is considered the author for purposes of this title, and, unless the parties have expressly agreed otherwise in a written instrument signed by them, owns all of the rights comprised in the copyright.
This is itself far from clear without some knowledge of Renaissance-era concepts of the ownership of created material that is, prior to the Statute of Anne (1710).1 Although we now identify works with their actual creators, that was certainly not the Renaissance practice; instead, works were owned by the creators' patrons, unless the creators were themselves independently wealthy and creating without prior commission. The Berne Convention, and the US Constitution, reject this formulation; however, it was statutorily reinserted by Congress in the early 20th century. We'll leave aside for the moment whether this was proper or not.2
So, in any event, it has landmines for both creators and their patrons. We'll clear away some of those landmines next time, leaving just the Claymores.
- Irrelevant aside: At the time it was passed, it was 1709... because the year began on 25 March. When the UK adopted the newer calendars in the mid-18th century, that same date moved from 1709 to 1710 when the year was started on 01 January (at the same time as the notorious loss of 11 days to correct for the excess number of leap years in the Gregorian calendar).
- The argument that it is not a constitutional exercise of Congress's powers is somewhat better than one might suspect. The Constitution empowers Congress to give to "authors" the rights in question, not to "authors and their patrons" a term with which the Founders were all too familiar, and with which Benjamin Franklin in particular had struggled over his years in and around the nascent publishing industry in the US. One might argue that the Commerce Clause and the Necessary and Proper Clause, collectively, give Congress the authority to do more than does the IP Clause itself. The problem is that the WFH definition does less than that by redefining "white" to mean "white and certain shades of grey and chartreuse." In other contexts, there is very strong and explicit precedent that Congress does not have the authority to change or refine definitions found in the Constitution; in particular, there's a strong line of cases in administrative, environmental, and maritime law that reserves that right to the courts.
This argument must wait for another time; I'm merely pointing out that it is not nearly so clear as most scholars, practitioners, and activists assume that it is, and probably points in opposition to that assumption.