Oh, Jeff, I'm the wrong one to throw cold water on cyber-optimism! But let me rummage around my closet and find my Arch-Conservative Hat, one I've been wearing less often these days, but still one I'm occasionally seen sporting.
There it is. OK, Jeff, Declan, let's talk about crime. Yes, crime, that nasty thing that sometimes reminds us that we do need a forceful, effective government. I'm not one who thinks that cyberspace is just one giant breeding ground for evil, but certainly the computer age doesn't materially diminish the risk of crime. As Michael Froomkin puts it, "no-one lives in cyberspace"; whatever nyms or hushmails we might use, murder, rape, robbery, child molestation, fraud, and terrorism all remain. And while crime has often been the excuse for government overreaching and undue invasion of privacy, some privacy (and yes, even liberty) must indeed be sacrificed in the name of safety. We have to somehow avoid both the police state and the "Where are the police when you need them?" state.
Traditionally, one vital tool for fighting crime has been the police search. Such searches should in most instances be difficult, but they shouldn't be (and aren't) impossible. With probable cause and a search warrant, the police can search even your home; and surely this must be the case, if we don't want to give everyone a safe haven to which they can retreat to hide their crimes.
Jeff, your book seems to praise the late-1700s rule that the police should not be able to search people's home, even with probable cause and a warrant, if they are searching for "mere evidence" of crime (outside the narrow areas of the fruits of crime, the instrumentalities of crime, or contraband). Can that really make sense? I think you suggest that courts were in some measure right to retreat from this rule (or perhaps you just reluctantly acknowledge that they're not going to restore it), and to allow broader searches; but you still demand that courts should limit such searches to really serious crimes. But given the hot controversies about which crimes are "really serious"--drug possession? Drug distribution? Gun possession? Large-scale fraud? Burglary? A felony allegedly committed by a government official entrusted to lead the most powerful military power on earth?--can such an approach really work?
More generally, Declan, you quoted Brandeis as saying that "sunlight is the most powerful of all disinfectants." But while that is especially true of the government, I don't think the insight can be limited to the government. Total security from police searches, either of your home or your encrypted computer, is a serious help to criminals, and a serious problem not just for the police but for the rest of us. And it becomes an even more serious problem when, given advances in modern technology, criminals can plot crimes that are deadlier than they ever were before.
Now, throughout this whole rant, my Libertarian Hat has been keening from the corner. What about police abuses, it wails? What about totalitarian oppression, always a possibility even in a 200-year-old democracy? And that's the tragedy: Most increases in government power to hunt crime are both dangerous and valuable, often to the same degree. The first police forces (creatures of the early to mid-1800s), the arming of the police, the ability of the police to use the telegraph to hunt down fugitives, and hundreds of other increases in law enforcement power could all have been rightly criticized as potential tools of oppression. But, sad to say, they were necessary tools nonetheless.
Or to consider another example that's waiting just around the corner: Some day soon, I suspect, the government will be able to maintain a national database of everyone's DNA, and easily track violent criminals (and many others!) to the scenes of their crimes. The clearance rate for stranger rape, I suspect, will skyrocket, as will our ability to deter and incapacitate rapists, and thus prevent rape. And there'll be a database that could let the government track us wherever we've left even a bit of tissue. Frightening--but so is the threat of rape, no? What should society do when it has to squarely confront this issue?
So, Jeff, Declan, what do you think? How do we protect our privacy against the government--both in cyberspace and out--but still allow the government to protect us against those who may often threaten much more than our privacy?