Copyright law often made up as we go along

Eric Zorn's article in the Chicago Tribune [via The Shifted Librarian] asks what are today's copyright norms:

Copyright law allows for what's called "fair use" of copyrighted material without payment or even consent of the creator. You can, for instance, quote freely from this column in your holiday newsletter without fear that the Tribune will ask the courts to seize rights fees from your wages.

But where's the line? What if you send your holiday newsletter to 100,000 people? If you copy the column for every student in every class in an entire school district? If you read every word of the Metro section on the radio?...

You can also take his cosmo-esque piracy / ethics test here. JD Lasica offers some results here.