Since 2018, the Internet Archive’s position, as articulated in a white paper by Duke University research librarian David Hansen and Harvard copyright adviser Kyle Courtney, has been that its digital files are protected under first sale doctrine and under fair use. Because the Internet Archive owns the physical book it is making its digital file out of, Hansen and Courtney maintain, it is allowed to do whatever it wants with that physical book, as long as it ensures a one-to-one “owned-to-loan” ratio. That’s the first sale doctrine part of the argument: As long as the Internet Archive only ever lends out one digital file at a time for every copy of a printed book it owns, this theory goes, it’s in the clear. And furthermore, because the Internet Archive is doing the whole thing to advance the cause of knowledge throughout the world, its actions fall under fair use. The theory is called Controlled Digital Lending (CDL).