There was recently an article describing Pirate Bay's wish to encrypt all traffic by default. After writing a comment about how to solve the privacy problem presented by application ports, I got to thinking: Why would I want to facilitate the distribution of illegal material by making it technologically more difficult for police to prove their cases?
The thing is that, right now in this article, we're talking about copyright violation and how Pirate Bay wants to help its users avoid getting sued. However, the term "illegal" applies to much more than just copyright violation or kiddie porn.
I think my doubt came out of the idea that legality is somehow confused with morality -- an idea that must be summarily rejected on principle. After all, here in the US, we have laws that go against certain religious principles. An example would be anti-polygamy laws and polygamist sects of major religions. Polygamy, for those people and people in other nations of the world is a perfectly acceptable and harmless part of society. So just in this one example, we have a case where the morality of a very large number of people would be in opposition to a certain set of laws.
Another huge example has to do with dictatorships and authoritarian governments who restrict the flow of ideas and information by making them illegal. Take for example the Great Firewall of China, which is used to restrict the flow of potentially subversive ideas into the country. Should the Chinese people be subject to these free speech restrictions? We in America and most of the West consider free speech as paramount in our cultures, but in China, free speech is illegal. We in the West would encourage Chinese to visit a blog where "subversive" democratic and capitalist ideas are discussed, but the Chinese government would probably arrest these people. So again, another disconnect between morality and legality. Whose morality? Whose legality? It depends on your perspective.
The point is that it's in the best interest of humanity to ensure that communication channels are as open as possible, regardless of "legality." Does this mean that some of them will be used for some sort of "universally immoral purposes"? Yeah, it'll always happen that way. However, the pros will always outweigh the cons when it comes to protecting the privacy of communication channels.
The inalienable right to free speech is absolutely required if you want to avoid the exercise of the right to bear arms. Oppressive governments making immoral laws should never be able to subvert the free exchange of ideas through use of threats to the person. To that end, technology and technologists must do their part to ensure that technology remains as neutral to "legality" and "morality" as possible.
For the police's part, they are still free to use other methods -- seizing specific computers, subpoenas of server logs, etc. However, the transport should never be subject to mass violation of privacy. It's too easy to spread a net over an entire population.