Here you have a new technology, and if that technology is going to work, you must allow people to provide central indexes of the data. It's just like a newspaper that publishes classified ads.
When you think of Napster, you think of music. But the first thing that struck me was that this was an important case not only for the music industry but for the whole Internet.
The very purpose of the Bill of Rights and the Constitution is to protect minority rights against majority voters. Every court decision that strikes down discriminatory legislation, including past Supreme Court decisions, affirming the fundamental rights to marry the person you love, overrules a majority decision.
The Audio Home Recording Act directly says that noncommercial copying by consumers is lawful.
Napster's only alleged liability is for contributory or vicarious infringement. So when Napster's users engage in noncommercial sharing of music, is that activity copyright infringement? No.