He's got it just about right--fair use

Lessig

. . .But there is one great and true part to DeLong's email. As he writes,

Causby was entitled only to the decline in his property value, not to a share of the gains from the air age.

Truly, if there is a principle here, that should be it. The baseline is the value of the property BEFORE the new technology. Does the new technology reduce THAT value. Put differently, would authors and publishers be worse off with Google Print than they were before Google Print?

To ask that question is to answer it -- of course the authors and publishers are better off with Google Print.

Are they as well off as they could be, if the law gives them the power to extort from the innovator some payment for his innovation?

To ask that question is to understand why this case has been filed: Like Valenti with the Betamax, the publishers and Authors Guild simply want to tax the value created by Google Print. They are not complaining about any "decline in [their] property value" caused by Google Print. They are instead racing to claim the value that ancient law is said to give to them, despite the harm that claim produces for "progress."