Regarding the April 19 Economy & Business article “Google wins legal battle over program to scan books”:

The Supreme Court bestowed great social benefits in declining to hear a challenge from authors arguing that Google’s digital library project violated copyright law. Twenty million books can be scanned; hopefully, magazines and newspapers will be next. What a world it will be when all of humankind’s knowledge is at our fingertips. And many other aspects of Judge Pierre N. Leval’s beautifully written decision at the federal appeals court level were worth noting.

The judge explained the history of fair use in the United States and how each of the statutory factors should be viewed when considering whether the use of someone else’s copyrighted material is a fair use or an infringement.

He clarified the length question that everyone would like an answer to. The test now is whether the amount used is “reasonably appropriate,” a standard he first helped develop in a law review article in late 2012.

The explanation has far-reaching effects for those who are battling specious take-down notices on the Internet. It makes clear that no numbers-based computer program can make a final determination about whether an Internet use is fair or not.

Michael C. Donaldson, Santa Monica, Calif.

The writer is a clearance lawyer for independent content producers.