And there are serious risks of legitimate content being blocked and service slowdown.

Unfortunately, filters don't understand fair use, and their use could result in legitimate content being kept offline.

It will mean that legitimate content is brought down because of similarity to illegitimate content.

"They've got to make it so the best choice is legitimate content," Mr. Perlman said.

It impairs access to legitimate content as well, and fails to stop child molesters.

There's probably a percentage of pornography mixed in, but one is not talking about legitimate content.

Take our discussion of peer-to-peer, for instance, with its lack of "legitimate content."

The album was well received containing legitimate lyrical content mixed with political and" good time" lyrics.

"We look at this as a first step in the peer-to-peer world, to try to steer people toward legitimate content," he said.

However, the trend among the attacks is to have legitimate content but bad intent.