Their justification was that the lockdown removed far more copies of the books from public library circulation than were ever checked out from the IA library. Something their checkout records easily confirm is true.

However this lawsuit isn't really about the lockdown period, it's about CDL as a whole.

There isn't even a legal basis for "controlled" online lending (or indeed much of what the IA does) But they've mostly always managed to keep things sufficiently non-provocative that it hasn't been a problem.