> And making a fair use defense ipso facto is an admission of using the work without permission (and thus making the preceding DMCA takedown valid).
Not quite right. Using work without permission is not the same as infringing on the copyright on the work, and a DMCA is a claim of infringement. Fair use can only be used as an affirmative defense, as you noted; only a court decides whether a use of a copyrighted work is fair use. But formally, fair use is not infringement according to the Ninth Circuit in Lenz v. Universal Music Corp. (2015) [1]:
> "Because 17 U.S.C. § 107[9] created a type of non-infringing use, fair use is 'authorized by the law' and a copyright holder must consider the existence of fair use before sending a takedown notification under § 512(c)."
Not that the Lenz ruling helped very much in practice. To meet the Lenz standard, the sender of the DMCA notice can claim in court that they believed in good faith that the use of the copyrighted work was not fair use. The only part of the initial DMCA notice that the sender writes under penalty of perjury is the claim of being the copyright holder or someone authorized to send the notice on behalf of the copyright holder [2]:
> (3)Elements of notification.—
> (A)To be effective under this subsection, a notification of claimed infringement must be a written communication provided to the designated agent of a service provider that includes substantially the following:
[omitted]
(vi)A statement that the information in the notification is accurate, and under penalty of perjury, that the complaining party is authorized to act on behalf of the owner of an exclusive right that is allegedly infringed.
In contrast, a party sending a counter notice - which they might be too intimidated to do in the first place, and otherwise happens before the rightsholder initiates court precedings - must dispute the initial DMCA notice under penalty of perjury [2]:
> (3)Contents of counter notification.—To be effective under this subsection, a counter notification must be a written communication provided to the service provider’s designated agent that includes substantially the following:
[omitted]
> (C)A statement under penalty of perjury that the subscriber has a good faith belief that the material was removed or disabled as a result of mistake or misidentification of the material to be removed or disabled.
The safest response by far for the recipient of the DMCA notice is to resign from contesting it i.e. let the service provider permanently remove the material.
[1] https://en.wikipedia.org/wiki/Lenz_v._Universal_Music_Corp.
[2] https://www.law.cornell.edu/uscode/text/17/512