Under the terms of the US Copyright act, chapter 12 para. 1201, every three years the Librarian of Congress is required to "determine whether there are any classes of works that will be subject to exemptions from the statute’s prohibition against circumvention of technology that effectively controls access to a copyrighted work."
In this year's determination
, the Librarian has designated six classes of works which are exempt from the DMCA's anti-circumvention provision. Category six, as determined by the Librarian, is:
(6) Literary works distributed in ebook format when all existing ebook editions of the work (including digital text editions made available by authorized entities) contain access controls that prevent the enabling either of the book’s read-aloud function or of screen readers that render the text into a specialized format.
It strikes me that the Librarian probably had in mind the visually impaired, who need to be able to listen to an ebook (mention specifically of "screen readers", for example). However, the determination does not appear to this IANAL's eye to specifically state that one's purpose must be to listen to an ebook, only that any DRM which prevents one from doing so may be lawfully circumvented.
While "screen readers" are generally software that reads to the visually impaired, could it conceivably include any ereader software? And is it sufficient that the DRM prevent my reader software of choice from reading, or could the rights holder designate a particular software? E.g., if a Kindle book can be read by the Kindle app, but not my screen reader of choice, am I still entitled to circumvent the DRM, or must I use the Kindle app?
I believe the Ligrarian's determination is legally binding, but I'm open to correction.