Content "filtering" raises many privacy concerns. In its most egregious form, content filtering can lead to a "Big Brother" George Orwell "1984" scenario. For instance, in Cuba, if a computer user types a "dissent" keyword, the word processor or browser is automatically closed, and a "state security" warning is given1. Fear of this type of heavy-handed usage is what fuels the most vocal and enraged critics2 of content filtering.
ISPs in some countries like China3, Burma4 and Iran5 are required to block certain internet addresses as an extension of State policy or dogma in order to squelch dissent and and "control" citizens. (In all, some two dozen countries are doing "political" web filtering (as well as filtering for other social and societal reasons6.)
For these reasons, we fully understand the need for judicious consideration of privacy when coming up with policies and techniques to combat online piracy and other potentially "dangerous" information on the net (like child pornography or how to make a nuclear device).
Online Piracy Privacy Issues
Implicit to stopping online piracy (by certain means) is knowing when it is occurring. So, if we know when it is occurring and who is doing it, that implies some sort of surveillance. That surveillance could constitute an invasion of privacy.
The question then is whether the invasion is justified and more importantly, legal given the facts of the case. Police in the U.S. can search someone's being, car, home, etc., if they have "probable cause." We are not lawyers and we do not want to get into the high legal weeds here, but so far in the United States and many other countries, courts have not taken the position that ISPs engaged in so-called packet sniffing or "deep packet inspection" are engaging in an unlawful search or trampling on one's privacy rights.
In fact, the U.S. Federal Communications Commission (FCC) tried to allege that recently with regard to actions taken by ISP Comcast and the U.S. Appeals Court told them to butt out.
Another hot-button issue is "catching" those who are engaged in illegal file sharing. In the old pre-internet days of copyright infringement, the infringement was either somebody ripping off the words and/or music to your song or making and distributing duplicate copies of your works. In both these cases, the baseline evidence—the copy itself and the individual doing the copying were relatively easy to prove.
In online piracy, they are the challenge. The way the internet is set up, to protect users as much as possible from being attacked in a myriad of ways, users are kept anonymous by their ISPs. Each is assigned an anonymous number, known as an "IP address." Moreover, the "copy" is electronic and once it disappears onto the computer of the downloader, behind that anonymous IP address, proving that it was even stolen is very difficult.
In other words, the theft takes place in a moment in time. It's digital, it's fleeting and once it's done, it's gone. It's not a CD you can hold in your hand or take to court and hand a judge and say: "see, here is the copy of my work and it has his (or her) name on it!!!"
So, to prove the infringement, you have to first find out the IP address. Then determine who the ISP is. Then, in the old days (pre-20047), the plantiff's counsel got a court subpoena sent to the ISP demanding they give up the name of the IP address holder. These days, one actually has to file a separate law suit in state court called a "John Doe" case to get the IP address holder's name.
After you know who you think infringed you, then you have to "prove" to the court that the infringement took place and that generally requires that you have hired (as substantial cost), some very expert computer/internet geeks that tracked the infringement and they have to show what they have and testify in court.
The cost to do all of this in federal court is huge. We have been quoted a minimum of $250,000 and many of the RIAA cases have costs in the millions to litigate.
Privacy rights advocates argue strenuously against these procedures for discovering who the alleged infringers are.