The news that the police departments in California routinely scan and record license plates to create a database that can be used to retroactively track any driver’s motions and activities broke at political and civil liberty websites and is now percolating through the autoblogosphere. Jack Baruth wrote about it here at TTAC yesterday. Jalopnik has picked up the story today. Like the current issue over NSA monitoring of electronic communication involves balancing national security with Americans’ privacy from government intrusion, recording and tracking license plates can be a useful tool in solving crime but it also seems contrary to American values and rights like freedom of motion and freedom from random surveillance without probable cause. Still, if I had a vote on the matter, since law enforcement in this country hasn’t exactly had a sterling record in protecting civil liberties, I wouldn’t trust them with this technology. Who knows how the political system will eventually deal with this news, but in the meantime remember that for every technology there is some way to defeat it. In this case, it might even be legal.
The law here in Michigan, and I assume it’s the same in most U.S. states, is that the registration information on your license plate has to be clearly legible and free of obstructions. Since people have been ticketed for license plate frames, tinted covers, and laser filters, putting any kind of cover over the plate would be legally problematic, or at least expose you to a traffic stop. I guess it hinges on how your particular cop and judge is going to define “clearly legible” and “obstruction”. It seems to me, though, that those legal terms have to do with human beings so you might be able to get away with some kind of polarized or interference filter that would mess with a digital camera but still be completely legible to a human. Still, as I said, putting anything directly over the plate might still get you a ticket.
Likewise, trying to use some kind of active lighting device that would blind the plate readers might also run afoul of statutes. I suppose there might even be some case law on using a device that interferes with traffic enforcement cameras. Actually, I’d be shocked if
the traffic enforcement and municipal revenue industry jurisdictions didn’t already make that illegal. So lasers and LEDs trying to blind the cops’ cameras directly are probably not a good idea.
Mulling this over, I thought about some of my own experience taking digital photos of cars (and license plates). I’m not a particularly great photographer, mostly a point ‘n shoot guy, but over the past three years I’ve taken tens of thousands of stereo pairs for the 3D content at Cars In Depth so it’s not like I’ve never tried to get a photo of a car’s license plate. Actually, once at a Camaro show I spent much of the day just shooting vanity plates. As I thought about jamming a plate reader and started going through Michigan state laws about registration plates and what’s legal and what’s not, if you’ll pardon the phrase, a light bulb went on. It’s possible that the very solution may exist in the Michigan Vehicle Code.
Every car in Michigan has to display its registration plate on the back of the car in, as mentioned, a clearly legible manner. Older cars that don’t have them as standard equipment are grandfathered in and exempt, but if your car was built after the federal motor vehicle safety standards were first introduced in the 1960s, your car must have a white light that illuminates your license plate at night, rendering it clearly legible at 50 feet behind the car.
MICHIGAN VEHICLE CODE (EXCERPT)257.686 Rear lamps; exemption; requirements for implement of husbandry; pickup camper.
Act 300 of 1949
(2) Either a tail lamp or a separate lamp shall be constructed and placed so as to illuminate with a white light the rear registration plate and render it clearly legible from a distance of 50 feet to the rear. A tail lamp or tail lamps, together with any separate lamp for illuminating the rear registration plate, shall be wired so as to be lighted whenever the head lamps or auxiliary driving lamps are lighted.
257.689 Clearance and marker lamps and reflectors; color.
(c) All lighting devices and reflectors mounted on the rear of any vehicle shall display or reflect a red color, except the stop light or other signal device, which may be red or amber, and except that the light illuminating the license plate shall be white.
So the law here says that I have to have a white light that illuminates my rear license plate that makes it clearly legible from a distance of fifty feet. Note that the law does not say that I can’t use a light that’s bright enough to make it visible at even longer distances. How bright my license plate lamp (and a “lamp” can have more than lighting element) can be does not appear to be regulated, provided it meets the minimum standards.
One of the things that I’ve learned shooting and processing those photos is that the human vision system is so much more sophisticated than even the most advanced digital or chemical camera. Your eyes can move in their sockets, your head can swivel and in real life your brain has terrabytes more information to work with than with photography, still or motion. What causes distortion or visual confusion in photography is not even noticed in real vision.
The above photograph of the ’63 split-window Corvette coupe was taken at the General Motors Heritage Center a couple of years ago and has not been modified other than cropping. I hadn’t yet learned that unless you’re using auxiliary lighting, when shooting in a large room, it’s best to turn off the flash and either let the cameras autoexpose or use manual settings. Otherwise, the flash ends up lighting the near field and everything in the background is dark. Also, when you use a flash you run the risk of the cars’ safety reflectors shining the light back at the camera, washing out part of the image.
As you can see from the photo, the effect also works with reflective license plates. The law says that I have to have a white light for my license plate that makes it visible from 50 feet. The law doesn’t say that I can’t make that light so bright that bouncing off the reflective surface of the license plate it would blind a digital camera. It also doesn’t say anything about light that is beyond the visible spectrum, like infrared. Since at least some of the plate readers use IR cameras, mixing in some IR with white doesn’t seem to me to violate the law. Actually, if the cameras work in the infrared spectrum, perhaps an array of heating elements that sufficiently warm the plate might defeat them.
It occurs to me that strobing the light at the right frequency might further interfere with the plate reader’s frame rate, but except for turn indicators, flashing lights are generally prohibited on non-emergency vehicles. As a matter of fact, most exterior lighting not used for road illumination or as otherwise required by law is prohibited. So undercarriage neon lights, or a neon license plate frame must not be illuminated when on the road. I’m not sure about coach lamps on broughams and landaus are quite legal then, but this would be another reason why an active system of additional lights trying to blind the cameras would be legally problematic.
That’s why using a super bright license plate light (or lights, the law doesn’t say you can’t have more than one) strikes me as an elegant solution. It’s not only legal, but you’re using equipment that the law says you must have on your car.
Please join in the conversation. Those with expertise in the law, optics and digital photography are particularly encouraged to share their informed opinions.
Ronnie Schreiber edits Cars In Depth, a realistic perspective on cars & car culture and the original 3D car site. If you found this post worthwhile, you can dig deeper at Cars In Depth. If the 3D thing freaks you out, don’t worry, all the photo and video players in use at the site have mono options. Thanks for reading – RJS