By Bruce Schneier
The Baltimore housing department has a new tool to find homeowners who have been building rooftop decks without a permit: aerial mapping. Baltimore bought aerial photographs of the entire city and used software to correlate the images with databases of address information and permit records. Inspectors have just begun knocking on doors of residents who built decks without permission.
On the face of it, this is nothing new. Police always have been able to inspect buildings for permit violations. The difference is they would do it manually, and that limited its use. It simply wasn't feasible for the police to automatically document every building code violation in any city. What's different isn't the police tactic but the efficiency of the process.
Technology is fundamentally changing the nature of surveillance. Years ago, surveillance involved trench-coated detectives following people down streets. It was laborious and expensive, and was only used when there was reasonable suspicion of a crime. Modern surveillance is the police officer sitting at a computer with a satellite image of an entire neighborhood. It's the same, but it's completely different. It's wholesale surveillance.
And it disrupts the balance between the powers of the police and the rights of the people.
Wholesale surveillance is fast becoming the norm. Security cameras are everywhere, even in places satellites can't see. Automatic toll road devices track cars at tunnels and bridges. We can all be tracked by our cell phones. Our purchases are tracked by banks and credit card companies, our telephone calls by phone companies, our Internet surfing habits by Web site operators.
Like the satellite images, the electronic footprints we leave everywhere can be automatically correlated with databases. The data can be stored forever, allowing police to conduct surveillance backward in time.
The effects of wholesale surveillance on privacy and civil liberties is profound, but unfortunately, the debate often gets mischaracterized as a question about how much privacy we need to give up in order to be secure. This is wrong. It's obvious that we are all safer when the police can use all possible crimefighting techniques. The Fourth Amendment already allows police to perform even the most intrusive searches of your home and person.
What we need are mechanisms to prevent abuse and hold the police accountable and assurances that the new techniques don't place an unreasonable burden on the innocent. In many cases, the Fourth Amendment already provides for this in its requirement of a warrant.
The warrant process requires that a "neutral and detached magistrate" review the basis for the search and take responsibility for the outcome. The key is independent judicial oversight; the warrant process is itself a security measure that protects us from abuse and makes us more secure.
This works for some searches, but not for most wholesale surveillance. The courts already have ruled that the police cannot use thermal imaging to see through the walls of your home without a warrant, but that it's OK for them to fly overhead and peer over your fences without a warrant. They need a warrant before opening your paper mail or listening in on your phone calls.
Wholesale surveillance calls for something else: lessening of criminal penalties. The reason criminal punishments are severe is to create a deterrent because it is hard to catch wrongdoers. As they become easier to catch, a realignment is necessary. When the police can automate the detection of a wrongdoing, perhaps there should no longer be any criminal penalty attached. For example, red-light cameras and speed-trap cameras issue citations without any "points" assessed against drivers.
Another obvious protection is notice. Baltimore should send mail to every homeowner announcing the use of aerial photography to document building code violations, urging individuals to come into compliance.
Wholesale surveillance is not simply a more efficient way for the police to do what they've always done. It's a new police power, one made possible with today's technology and one that will be made easier with tomorrow's. And with any new police power, we as a society need to take an active role in establishing rules governing its use. To do otherwise is to cede ever more authority to the police.
Schneier.com is a personal website. Opinions expressed are not necessarily those of BT.