WOOTxELEVENTY!!11!1!!1! I fought the law...
06-13-2007, 06:07 PM
#1
AudiWorld Super User
Thread Starter
WOOTxELEVENTY!!11!1!!1! I fought the law...
And I won.
For those that are interested, here is my recount of how I beat a LIDAR ticket in Boulder Municipal Court today.
Warning: arguments full of geek-speak follow. And it's very (OK, extremely) long, probably because I'm overly proud of the experience... so stop here or don't complain.
I got a speeding ticket in Boulder in April, which I decided to contest based on the methods used. When I talked to the city attorney at arraignment, she showed me the officer's notes on the back of the ticket. It said that he took the LIDAR reading through his side-view mirror. This raised some suspicions with me, and <soapbox> I felt it was my moral obligation to my fellow motoring humanity to fight any new technology or methods used for speed trap revenue generation. Even though I only gave myself a <50% odds of winning going into court today, I was doing it as a public service </soapbox>.
Following is a recap of all the arguments I presented, and which ones seemed to get traction with the judge. Use at your own discretion, and bear foremost in mind that a different judge would probably draw different conclusions given their general lack of scientific education.
Argument 1: My recollection of where the cop was parked differed from his. I didn't bring any witnesses to back up my version, so it was basically word against word, and I figured the judge was not going to favor that kind of argument. Plus, the only reason for the argument was to attempt to invalidate the whole citation based on a description error, and she didn't seem to be going for it -- so in the interest of not annoying the court I dropped it pretty quickly.
Argument 2: No evidence from the city that the LIDAR device was tested after the stop or at end of shift. The prosecutor did a lame job of trying to cover this point, but ended up only getting that the officer "probably" worked the following day, and would have "normally" tested it again at the beginning of his shift. Judicial notice for use of LIDAR says the device should be tested at beginning *and* end of shift on the day of citation, and she didn't prove the second. Judge said she would have accepted testing at the beginning of the next day, but the testimony on that was "probably" he worked, without certainty.
Argument 3: Visual estimate of speed doubtful. Officer is trained to visually estimate speed of vehicles within ±5mph in traffic, but all training is done in direct sight (cop watching traffic while standing on the side of the road). In this instance, the officer was watching and estimating from his side-view mirror. My contention was it's a somewhat different perspective and thus skill watching through a small mirror. I didn't push it really hard, and the judge didn't seem to latch on.
Argument 4: Questionable signal effects due to using the LIDAR through the mirror rather than direct line-of-sight.
4a: Signal alteration / error introduction due to vibration. The officer testified under cross that his vehicle was idling during the time of measurement (naturally, so as to minimize his delay in making the stop after collecting a reading). I contended that there was a substantial possibility that the vibration of the mirror due to the vehicle's engine running could affect the LIDAR measurement. I threw down some geekness about how LIDAR technology, under the name of laser interferometry, is used in industrial applications to measure vibrations and other small-scale movements. The fundamental technology is so sensitive that it could easily measure the speed of the mirror moving back and forth, either confusing or replacing the measured speed of the target vehicle. The judge pushed and asked me for a concrete example, so I described using a laser interferometer to characterize vibration and response frequencies of disk drive components in industiral labs. I allowed that it's entirely possible that the device manufacturer has anticipated and filtered for such error, but the prosecution holds the burden of proving the integrity of the device AND methods, and this method was not covered in the cases already under judicial notice.
4b: Signal degradation due to glass. I argued that the BPD has a guideline that officers should not aim the LIDAR through a vehicle window because of the degrading effect on signal. I provided the court a diagram explaining how shooting the laser through a window accumulates two passes through glass (which will attenuate the signal), and how shooting through a mirror actually accumulates *four* passes through glass (since the reflective surface is on the back of the mirror). I could not testify as to exactly what the effect on the signal would be, but I felt that by extrapolation of the department's own guidelines, 4 must be worse than 2.
Neither 4a nor 4b are covered in the cases accepted for judicial notice which underpin all the LIDAR convictions the court hands down.
Argument 5: This one I came up with on the fly... The ticket said the officer made a visual estimate of 55mph at a range of 700 feet. His official reading from the gun said 59mph at 458 feet. He testified that the LIDAR usually takes 1-2s to acquire a signal lock, and that he held the lock for 2-3s (minimum 2s is required under the judicial notice case guidelines). Some rough calculations I did while the prosecutor was making her closing argument led me to a suspicion. 55mph is about 85 feet/s (I now know it's 80.6, but I was estimating in a hurry). So between his estimate at 700' out, I would have had to travel 85f/s for 3-5s = 255-425'. But the LIDAR said it stopped taking readings (when he let off the trigger after 2-3s) at 458', only 242' from the estimate location. This means either his estimated speed was high, the distance was low (and when asked under cross about gauging the distance, he said he uses regular hangouts and is very familiar with landmarks in those areas), or his whole testimony about typical timing or having held the lock for >2s was in question. Here the judge threw up some bad math and said she interpreted ±5 as "being within 10 of the actual" (I had to stifle a scream...), and she wasn't leaning too heavily on the visual estimate being very accurate.
[ My favorite segment of the prosecutor's cross of my testimony:
City Attorney: Are you an optical engineer?
Me: No Ma'am, I'm a mechanical engineer.
CA: Have your had any formal training in LIDAR devices?
Me: Not in a university setting, but I have had in an industrial laboratory setting.
CA: <crickets> ]
After almost an hour of total time (twice as long as I thought it would take), the judge's verdict: Dismissed!!! She was careful to limit the interpretation of her ruling, elaborating that she based it on two points.
A: the failure of prosecution to prove that the LIDAR had been tested at or near the end of the shift.
B: the 4-times-thru-the-glass concern. She agreed with me that the methodology wasn't affirmatively proven to the point that this concern should be dismissed. (This is really ironic, because from a physics standpoint the vibration theory holds waaaaaaay more water than the glass-effect theory.)
So there it is. I felt like Jack Frickin' McCoy walking out. I must conclude with two points:
1) The odds of a different judge coming to the same conclusions on all the arguments is almost nil, I think. But I managed to beat a LIDAR ticket based on the police using a new method even though the department itself has reportedly conducted extensive testing to convince themselves the method is valid.
2) The City Attorney, the Officer, and the Judge were all fantastic. They were accommodating, friendly, and courteous at every stage. The officer and CA even shook my hand after and said "Good job". I told the officer that my motivation was explicitly not personal, but purely that I thought his bosses should have him doing other work besides speed enforcement (and I believe this strongly). His response, smiling: "Hey I never take it personally - I enjoy a good challenge!" His demeanor was like I had just beat him at a game of ping-pong (and he figured he would win the next one).
[My second-favorite quote, parting comment from the CA: "Darn you engineers!" She was smiling, though.]
And also an acknowledgement - I got some supporting advice from somebody I know at a manufacturer of military/commercial laser devices. That helped me chase down the vibration theory.
For those that are interested, here is my recount of how I beat a LIDAR ticket in Boulder Municipal Court today.
Warning: arguments full of geek-speak follow. And it's very (OK, extremely) long, probably because I'm overly proud of the experience... so stop here or don't complain.
I got a speeding ticket in Boulder in April, which I decided to contest based on the methods used. When I talked to the city attorney at arraignment, she showed me the officer's notes on the back of the ticket. It said that he took the LIDAR reading through his side-view mirror. This raised some suspicions with me, and <soapbox> I felt it was my moral obligation to my fellow motoring humanity to fight any new technology or methods used for speed trap revenue generation. Even though I only gave myself a <50% odds of winning going into court today, I was doing it as a public service </soapbox>.
Following is a recap of all the arguments I presented, and which ones seemed to get traction with the judge. Use at your own discretion, and bear foremost in mind that a different judge would probably draw different conclusions given their general lack of scientific education.
Argument 1: My recollection of where the cop was parked differed from his. I didn't bring any witnesses to back up my version, so it was basically word against word, and I figured the judge was not going to favor that kind of argument. Plus, the only reason for the argument was to attempt to invalidate the whole citation based on a description error, and she didn't seem to be going for it -- so in the interest of not annoying the court I dropped it pretty quickly.
Argument 2: No evidence from the city that the LIDAR device was tested after the stop or at end of shift. The prosecutor did a lame job of trying to cover this point, but ended up only getting that the officer "probably" worked the following day, and would have "normally" tested it again at the beginning of his shift. Judicial notice for use of LIDAR says the device should be tested at beginning *and* end of shift on the day of citation, and she didn't prove the second. Judge said she would have accepted testing at the beginning of the next day, but the testimony on that was "probably" he worked, without certainty.
Argument 3: Visual estimate of speed doubtful. Officer is trained to visually estimate speed of vehicles within ±5mph in traffic, but all training is done in direct sight (cop watching traffic while standing on the side of the road). In this instance, the officer was watching and estimating from his side-view mirror. My contention was it's a somewhat different perspective and thus skill watching through a small mirror. I didn't push it really hard, and the judge didn't seem to latch on.
Argument 4: Questionable signal effects due to using the LIDAR through the mirror rather than direct line-of-sight.
4a: Signal alteration / error introduction due to vibration. The officer testified under cross that his vehicle was idling during the time of measurement (naturally, so as to minimize his delay in making the stop after collecting a reading). I contended that there was a substantial possibility that the vibration of the mirror due to the vehicle's engine running could affect the LIDAR measurement. I threw down some geekness about how LIDAR technology, under the name of laser interferometry, is used in industrial applications to measure vibrations and other small-scale movements. The fundamental technology is so sensitive that it could easily measure the speed of the mirror moving back and forth, either confusing or replacing the measured speed of the target vehicle. The judge pushed and asked me for a concrete example, so I described using a laser interferometer to characterize vibration and response frequencies of disk drive components in industiral labs. I allowed that it's entirely possible that the device manufacturer has anticipated and filtered for such error, but the prosecution holds the burden of proving the integrity of the device AND methods, and this method was not covered in the cases already under judicial notice.
4b: Signal degradation due to glass. I argued that the BPD has a guideline that officers should not aim the LIDAR through a vehicle window because of the degrading effect on signal. I provided the court a diagram explaining how shooting the laser through a window accumulates two passes through glass (which will attenuate the signal), and how shooting through a mirror actually accumulates *four* passes through glass (since the reflective surface is on the back of the mirror). I could not testify as to exactly what the effect on the signal would be, but I felt that by extrapolation of the department's own guidelines, 4 must be worse than 2.
Neither 4a nor 4b are covered in the cases accepted for judicial notice which underpin all the LIDAR convictions the court hands down.
Argument 5: This one I came up with on the fly... The ticket said the officer made a visual estimate of 55mph at a range of 700 feet. His official reading from the gun said 59mph at 458 feet. He testified that the LIDAR usually takes 1-2s to acquire a signal lock, and that he held the lock for 2-3s (minimum 2s is required under the judicial notice case guidelines). Some rough calculations I did while the prosecutor was making her closing argument led me to a suspicion. 55mph is about 85 feet/s (I now know it's 80.6, but I was estimating in a hurry). So between his estimate at 700' out, I would have had to travel 85f/s for 3-5s = 255-425'. But the LIDAR said it stopped taking readings (when he let off the trigger after 2-3s) at 458', only 242' from the estimate location. This means either his estimated speed was high, the distance was low (and when asked under cross about gauging the distance, he said he uses regular hangouts and is very familiar with landmarks in those areas), or his whole testimony about typical timing or having held the lock for >2s was in question. Here the judge threw up some bad math and said she interpreted ±5 as "being within 10 of the actual" (I had to stifle a scream...), and she wasn't leaning too heavily on the visual estimate being very accurate.
[ My favorite segment of the prosecutor's cross of my testimony:
City Attorney: Are you an optical engineer?
Me: No Ma'am, I'm a mechanical engineer.
CA: Have your had any formal training in LIDAR devices?
Me: Not in a university setting, but I have had in an industrial laboratory setting.
CA: <crickets> ]
After almost an hour of total time (twice as long as I thought it would take), the judge's verdict: Dismissed!!! She was careful to limit the interpretation of her ruling, elaborating that she based it on two points.
A: the failure of prosecution to prove that the LIDAR had been tested at or near the end of the shift.
B: the 4-times-thru-the-glass concern. She agreed with me that the methodology wasn't affirmatively proven to the point that this concern should be dismissed. (This is really ironic, because from a physics standpoint the vibration theory holds waaaaaaay more water than the glass-effect theory.)
So there it is. I felt like Jack Frickin' McCoy walking out. I must conclude with two points:
1) The odds of a different judge coming to the same conclusions on all the arguments is almost nil, I think. But I managed to beat a LIDAR ticket based on the police using a new method even though the department itself has reportedly conducted extensive testing to convince themselves the method is valid.
2) The City Attorney, the Officer, and the Judge were all fantastic. They were accommodating, friendly, and courteous at every stage. The officer and CA even shook my hand after and said "Good job". I told the officer that my motivation was explicitly not personal, but purely that I thought his bosses should have him doing other work besides speed enforcement (and I believe this strongly). His response, smiling: "Hey I never take it personally - I enjoy a good challenge!" His demeanor was like I had just beat him at a game of ping-pong (and he figured he would win the next one).
[My second-favorite quote, parting comment from the CA: "Darn you engineers!" She was smiling, though.]
And also an acknowledgement - I got some supporting advice from somebody I know at a manufacturer of military/commercial laser devices. That helped me chase down the vibration theory.
06-13-2007, 06:24 PM
#3
AudiWorld Expert
Congrats Good work = though I don't condone speeding (moral voice of AW :) )
You did a great job of showing the officer was not right in what he/she did.
BTW - In the late 80s a HP R&D manager friend of mine got off of a radar ticket for 130+ in Nevada in his 530i using technical analysis like you did.
BTW - In the late 80s a HP R&D manager friend of mine got off of a radar ticket for 130+ in Nevada in his 530i using technical analysis like you did.
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06-13-2007, 08:49 PM
#10
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MEs unite!! Good work
I beat one about a month ago because (I think) I confused the city attorney during a prelim meeting with a few pages of data and calculations. When it comes to traffic tickets, an engineer's education is priceless 
lol
lol