What's the best way to record the cops? Here's a quick run-down of the choices.

Cameras without wireless networking capabilities are the least attractive option. If they are destroyed or confiscated in the field, you probably have lost the damning video you just recorded, including any footage documenting how your camera was confiscated or destroyed. But provided you can hold on to your machine, digital video recorders today are inexpensive, small, and practical. The most popular easy-to-use brand right now is the Flip Video line of cameras, which start at $149. Even the cheapest Flips fit in your pocket, power up in about three seconds, and feature one-button recording. They include a built-in USB port and instant formatting for hosting sites such as LiveLeak and YouTube.

Kodak also has a pocket video camera for $100, and Amazon.com lists a couple dozen different flash-memory video cameras for under $50. Still too expensive? For $20, a camera sold at the USBGeek website is shorter than a stick of gum and shoots 640×480 video at 30 frames per second. Its memory slot will hold up to 32GB of memory, and it has a two-hour battery life. Meritline.com sells a keychain camera that's tiny, has the advantage of not looking much like a camera, shoots 720×480 video at 30 frames per second, and sells for all of $12 (with free shipping).

If your camera is confiscated by the authorities and you find after it has been returned that your files or videos have been deleted, your best option is to look into recovery software, which in many cases can bring the deleted files back. Don't use the camera or phone until you've tried the software.

Ideally, you want a camera with wireless capability and access to a network speedy enough for instant online streaming. Technology is helping there too. We are increasingly seeing spy-movie-style cameras like the Bluetooth device from Looxcie, which hangs on your ear and lets you instantly email video.

The ability to store audio or video off site—to email it to friends (or yourself), or to upload it to social networking sites—is becoming more and more accessible. In fact, it's now standard in most smart phones.

Qik and UStream, two services available for both the iPhone and Android phones, allow instant online video streaming and archiving. Once you stop recording, the video is saved online in seconds. Both services also allow you to send out a mass email message or a notice to Twitter followers when you post a new video from your phone.

Neither Qik nor UStream markets itself for this purpose, and it probably would not make good business sense for them to do so, given the risk of angering law enforcement agencies and attracting attention from regulators. But it's hard to overstate the power of streaming and off-site archiving. Prior to this technology, prosecutors and the courts nearly always deferred to the police narrative. Now that narrative has to be consistent with independently recorded evidence. And as examples of police reports contradicted by video become increasingly common, a couple of things are likely to happen: Prosecutors and courts will be less inclined to uncritically accept police testimony, even in cases where there is no video, and bad cops will be deterred by the knowledge that their misconduct is apt to be recorded.

But there is still room for improvement. With both Qik and UStream, uploaded videos can be deleted from the phone, which means that if your phone is confiscated before you can turn it off (or if you keep your phone unlocked), authorities can get into your account and erase your evidence. One not terribly reliable way around this problem would be to encourage any of your friends or Twitter followers who happen to be online at the time to download your video the moment they get notice of it. But a far better option would be an upload service that allows videos to be deleted only through a password-protected account accessed from a computer. Another improvement would be the ability to "black out" your phone while it's taking video, so it isn't so obvious that you are recording.

UStream and Qik probably aren't likely to add either function, since both are beneficial only for people who want to make surreptitious recordings. But an organization such as the American Civil Liberties Union or the National Association for the Advancement of Colored People might consider developing a cell phone app specially designed for recording police. The NAACP's "All Alert" project encourages people to report incidents of police abuse through a toll-free phone number, text message, or Twitter. But the process for registering a complaint is pretty cumbersome, and the program doesn't allow instant streaming and archiving.

Scott Morgan of Flex Your Rights, an organization that informs people about their rights during police encounters, says his organization has been exploring the possibility of offering such a service. "I think it's a great idea," Morgan says. "We've talked to a couple developers about it. I think the problem for a small group like us is getting server space for videos and working out the networking issues." Globally, it would make great sense for an organization such as Amnesty International or Human Rights Watch to develop a similar easy-to-use application, allowing people all over the world to emulate instant documentation of the sort we saw during the 2009 protests in Iran.

The dizzying advancements in personal technology during the last decade have slipped a powerful government accountability tool into our pockets. But it happened mostly by accident. The technology was intended for other uses, and it still needs some fine-tuning to work better as a protection against abuses of state power. Doing so would be a worthwhile project for an organization dedicated to preserving civil liberties.

Radley Balko is a senior editor at reason.