Justice, we are not making an empirical claim at all. Nothing in our Copyright Clause claim hangs upon the empirical assertion about impeding progress. Our only argument is, this is a structural limit necessary to assure that what would be an effectively perpetual term not be permitted under the copyright laws.
This case has witnesses
( z1 have :ARG0 ( z2 case :mod ( z3 this ) ) :ARG1 ( z4 person :ARG0-of ( z5 witness ) ) )