Coright 教授的意見——————關於24小時內下載刪除問題：

The U.S. Copyright Act prohibits any reproduction of a copyrighted work; it doesn't say anything about single copies, non-commercial copies, copying for private use, or copies of limited duration. It leaves all of those considerations to the "fair use" doctrine (which is a defense). Thus, any reproduction, even a temporary one, is infringing UNLESS it is a fair use (or falls within one of the other exemptions).

Whether this would be a fair use depends on the circumstances. In the Sony Betamax case, the U.S. Supreme Court held 5-4 that reproducing broadcast TV for time-shifting purposes (to watch it at a later time) WAS
a fair use, but strongly implied that keeping library copies permanently would not be a fair use. That is why people might think that copying something to watch or listen to later and then deleting it is a fair use. However, the Sony decision was heavily dependent on the
advertiser-supported business model of broadcast TV; people didn't pay to watch TV, the advertisers paid for the show through buying commercials, so the copying didn't deprive the copyright owner of any revenue.Whether
downloading something off a website deprives a copyright owner of any revenue is more debatable and depends on the specific circumstances. If you have to pay a subscription service to listen to the music, then even
downloading for just 24 hours might be considered infringing and not a fair use.

So,there's no definitive answer.I do think it is extremely unlikely that anyone who downloads for only 24 hours and deletes will be detected or sued, but of course there are no guarantees. Personally, I would not download a commercial recording even for 24 hours without
authorization, unless the recording were out of print or otherwise not commercially available; and I think a court would not extend the Sony doctrine beyond its specific facts. But that's just my opinion. :-)