Tuesday, September 29, 2009

GPS Evidence Legislation/Regulation - Part II

In January 2009, I wrote a post calling for Uniform GPS evidence regulation/legislation. You can find that post here, including my wish list for such regulation.

Since that time, three more cases have gone through state courts, and its my recollection that all three courts called for legislation. Wisconsin's court of appeals allowed warrantless GPS tracking evidence admission, but called for legislation and regulation of the practice. New York required a warrant under the New York State constitution (not under the Federal constitution) in part because of the lack of state regulation of GPS tracking evidence. Massachusetts approved GPS evidence obtained with a warrant, but strictly regulated (by judicial mandate) even warranted GPS evidence collection, again, in the absence of state regulation on the subject, and under the Massachusetts constitution. So, state courts are asking their own legislatures for GPS legislation and regulation.

In addition to my previous post, I will run through the reasons why GPS evidence regulation not only benefits all of society, but specific groups that have an interest in GPS evidence regulation:

Why these groups should support GPS regulation:
1. Law enforcement & prosecutors: I believe most of those who are in law enforcement want to go by the rules, because going by the rules get convictions that are not overtured, and going by the rules gives the best chance that guilty parties are going to jail rather than innocent people. Right now, there are no rules (except the previous caselaw, which, while clear, doesn't provide much guidance) so law enforcement may be tempted to "push the envelope." How many cases could be overturned, and guilty parties released, if the courts suddenly find current police practices too intrusive? However, if state legislatures make systematic, clear rules, law enforcement can use GPS evidence with confidence, without the concern that the state courts will later throw out dozens, or hundreds, of cases where GPS evidence led to a conviction or led to other evidence that led to a conviction.

Prosecutors are being overwhelmed with numbers. GPS evidence, because it is high quality evidence, (See my blog posting on the "Economics of GPS evidence") induces guilty pleas in the guilty very early in the process. This, in turn, cuts down on handling the "iffy" cases at an early stage so prosecutors can concentrate on the important cases, trying more cases and giving better public enforcement.

2. Public and Private Criminal Defense Bar- Public Defenders serve an ever growing number of the citizen accused. Some are guilty of a crime, some are truly innocent, and some have committed a crime, but law enforcement can't prove it. Unfortunately for public defenders, not all the guilty admit their guilt. The truly guilty look a lot like the truly innocent, and their aren't enough resources to take every case to trial. Even if there were, there aren't enough hours in the day for everyone to get an appropriate defense. Accordingly, both the prosecution and the defense engaging plea bargaining. With plea bargaining, innocent defendants might agree to a conviction because of the threat of even worse punishment if the state can somehow make the case. Innocent defendants may not have confidence in their overworked public defenders to win the case even if they are innocent.

GPS evidence will cut down the number of "iffy" cases by showing the guilty high quality, convincing evidence of their guilt. Public defenders then will have more time to devote to those who, on the surface, appear truly innocent, or at least have little evidence against them. Of course, public defenders will never have to see those GPS evidence exonerates, as law enforcement will look at the GPS evidence and conclude there is no use bringing charges against them.

Finally, if public defense investigators can track those who are actually guilty of the crimes that the public defender clients are accused of, they can swiftly bring the guilty to justice while exonerating the innocent.

3. Victims - GPS evidence will jail the true perpetrators of crime, rather than the most convenient person that doesn't have an alibi. Victims do not prosper by the incarceration of the innocent.

4. Courts - Courts are crowded, justice is delayed because of cases with low quality evidence. GPS evidence, by settling cases quickly, determining guilt in a fashion that the guilty can clearly recognize, will cut down on trials and allow the court to sentence the guilty with confidence. Clear guilty verdicts also mean fewer appeals, as who would appeal a clear cut confession and guilty plea based on being caught with GPS evidence?

Of course, the unstated problem is that no one wants a society of police officers who spend their time constantly monitoring the same GPS units, hooked to the same cars, waiting for those they have predetermined are guilty to slip up. I would term such law enforcement practice locational myopia. GPS evidence is a tool, but without safeguards, it will become a crutch, and a weak crutch at that. The safeguards come the form of legislative limitations:

1. How GPS evidence can be distributed and used: The concerns of Washington's Supreme Court are real- GPS evidence can be one of the most powerful tools for blackmail known to man. However, if treated like medical records (equally potent), legislative action can criminalize the distribution of legitimately gathered GPS evidence for illegitimate purposes. The legislature can designate ways GPS evidence can be stored, handled, anonamously warehoused (with identification for possible later use, but only by trusted experts.)

2. How GPS evidence can be gathered (without consent or waiver)- It is clear that police, under the current law, can legally attach tracking devices to cars in public places, if those devices don't have to be connected to the vehicle's electrical system. However, problems will occur if the public start putting GPS devices on cars. Altercations will occur. While the author does favor some form of public ability to GPS track, it should be through a reasonable process - the GPS unit's serial number recorded, the vendor noted, and website (if any) disclosed, a fee charged, and public officer, private investigator or police agent charged with placing the unit, just as we have police or third parties serve documents. Placing a GPS should be licensed, as should retrieval of the data (unless done remotely through a website) to preserve integrity of the process. This would protect the person requesting GPS evidence from charges of "stalking." Then, if someone finds a GPS on their vehicle that is not authorized by law, legislation should provide criminal penalties for the person who placed it.

3. How GPS evidence can be admitted into court - Since GPS evidence is so powerful, the legislature should promulgate chain of evidence rules to make sure the evidence presented is really what it proports to be. GPS evidence that doesn't comply to strict standards should be excluded.

4. Who should be excluded from rules - Some types of GPS evidence should be excluded from the rules, such as tracking one's own property, employer tracking (with prior warning & waivers), parent tracking of minor children, tracking those who have been adjudicated incompetent (for their own safety), or anyone a court determines should be excluded from restrictions (by petition to the court under particular circumstances by ex parte order.) Fraud in such a petition should be criminally punishable, and GPS evidence obtained from a fraudulent petition excluded from admission before the court.

5. How long tracking should be allowed without returning to an authority - GPS tracking of a citizen for an indefinite time frame, while technically possible, is morally repugnant. There are circumstances, however, where the tracking party should be allowed long time periods of GPS tracking to continue to collect the most evidence. For instance, where a short period of tracking discloses a criminal conspiracy, short periods of time might be insufficient to disclose the entire extent of the conspiracy. In such circumstances, extended GPS tracking, including multiple tracking, would allow the fullest disclosure of arrangements that are designed to be secret.

I'd love to be able to provide the perfect blueprint for GPS legislation, but in a democracy, such a blueprint only will come from open hearings involving all the possible interested parties, including potential victims, the public, the investigators, the prosecution and the defense. I hope this opens a dialog and starts a discussion. Waiting for the courts is not an option, as many of the courts themselves recognize they are not the appropriate place for these issues to be regulated and decided.

Thursday, September 24, 2009

GPS Evidence-Avoiding Locational Myopia-Opponent

GPS Evidence may be one of the greatest criminal and civil evidentially breakthroughs of the twentieth century, able to convict the guilty and exonerate the innocent. Its potential is right up there with DNA, and its cost-benefits are much better than DNA.

However, although it is a powerful tool, it is still just a tool. That is why it needs regulation. It's too easy to turn every crime or civil problem into a locational issue - thereby missing real, perhaps contradictory, evidence.

I agree with Attorney John Ganz that public travels are "already public,"(see article at left) and therefore one needs no warrant to examine what, for lack of a better term, is in "plain view," not only of law enforcement, but of everyone. But unfettered and unregulated GPS tracking invites abuse in just the same fashion that unfettered wiretapping invited abuse a generation ago. Warrants are not the manner of applying that regulation. Legislation is.

Courts cannot, for all their attempts, institute comprehensive, well thought out regulatory schemes. Courts cannot take in all the possible factual situations that come before the court. They don't have the resources legislatures do. When courts attempt to regulate, they end up finding exceptions to their own rules, redefining their own rules, and even overruling their own rules. Courts can do this, because a rule created by the court is no more certain than the next case to come along, and the court has the power to overrule itself.

Court-created legislation creates uncertainty. Uncertainty, without a doubt, is bad for the progress of a civilized society. Courts function best when interpreting well thought out legislation, filling in the holes.

So why legislation? Why shouldn't GPS be unfettered? Too much reliance on GPS can lead
to what I call a version of the Peltzman effect, that "people to react to a safety regulation by increasing other risky behavior, offsetting some or all of the benefit of the regulation." (Wikipedia definition). When it comes to GPS evidence, I see the possibility of investigators and prosecutors so relying on GPS evidence that they might fail to gather potentially more persuasive evidence. Furthermore, myopic investigators might fail to fully investigate GPS evidence using physical facts, and thus be prey to being misled by false or misleading GPS evidence.

While this hasn't happened yet today, as even law enforcement is just learning to trust GPS, its not too soon to prevent over-reliance on a single tool. DNA is such a tool. Wisconsin set up a system to gather DNA samples from all those incarcerated some years ago, then relied on those samples to either accuse or excuse the "donor." Unfortunately, officials recently found about 12,000 samples were missing. Without checks and balances, even great tools like DNA and GPS evidence can lead to false security and myopia.

GPS Evidence-Waiving Possible Location-Based Evidentiary Rights

There is no question that in many jurisdictions, there are open questions as to whether individuals have a right to keep their location information private from tracking by GPS devices. While this is ironic, because no one can argue that public travel that is exposed to the naked eye is private, some courts have, based on state constitutions, found specific rights to be free from GPS tracking, at least by law enforcement. Furthermore, legislatures and the Federal Government may (and should, according to this author) put reasonable limitations on GPS tracking and the admissibility of the evidence it creates, thus creating limited rights not to be tracked.

Where rights exist, the ability to waive those rights exists. Everyone has heard of Miranda rights given to accused individuals by police officers, just before the accused is given an opportunity to waive those rights and talk with the officer. There is no reason any right to be free from locational GPS tracking cannot be waived, if rights as important as the Miranda rights can be waived. Just because a right hasn't been established doesn't mean that someone can't waive that right, should it be recognized. So, what should prudent prosecutors, attorneys, insurers, child support enforcers and employers do? Place GPS evidence collection and introduction waiver clauses in every contract, agreement, employment manual, court order, plea agreement, bond condition that crosses their desk. Just because today you can't think how to use GPS evidence doesn't mean tomorrow you won't. Waivers give the holder the right to collect and use GPS evidence where the rest of the world might not. Make sure to include the right to collect GPS evidence, as without it, you'll have nothing to introduce in court.

How might such waivers work? Take child support collection. Countless single parents have to raise children on their own income alone because payor parents find ways to work in "undocumented" jobs. Child support enforcement attorneys have the difficult task of "proving" the payor had employment with a virtual vacuum of information. How could GPS waivers help?

Employment has certain characteristics. First, it usually takes travel. Two, it takes time, usually upwards of 8 hours a day. Three, it is usually "periodic" and follows a set schedule.

Step 1: At the first possible hearing, the Child Support Enforcement Attorney requests (and probably will get) the GPS evidence collection and use waiver from the court. Of course, since it doesn't guarantee GPS monitoring, payor without visible employment might take efforts to avoid GPS tracking at first , but eventually will fall back into an ordinary routine.

Step 2: After a reasonable amount of time, Child Support Enforcement commences tracking. If it shows no pattern that would show employment, very few resources are lost (simply the time to review the track), and the investigator goes on to the next potential payor. However, if there is a pattern of employment (regular stops at factories, places of business, etc. with extended stays.) the investigator goes on to the next step.

Step 3: The investigator stakes out the potential employment site at the time the payor usually arrives and photographs entry and leaving times. If the GPS track shows regular periods, the investigator need only stay at the site long enough to get photos entering, then return to get photos leaving.

Step 4: The investigator finally consults with other law enforcement about suspicions of undocumented employment. Law enforcement can either confront the employer about the allegations, who will likely cut a deal and give evidence about the payor, or confront the payor with a deal (including back support) to give evidence on the employer.

The beauty of such a system is that, once the waiver is in place, the payor can't ever tell if he is being tracked. After a few cases of GPS child support enforcement hit the papers, payors will either start to sweat about whether there will be a knock on their door, or get valid, documented employment that the payee parent can get enforcement from.

Any periodic activity lends itself to this kind of tracking- workers compensation fraud (track them to the bowling league or baseball field), employee moonlighting, etc.

There is no downside to getting a GPS waiver in a contract as soon as possible.

Sunday, September 20, 2009

GPS Evidence-Revolutionizing Auto Risk Analysis?

Traditionally, auto insurance premiums have been determined by a number of general factors - driver age, drivers address, past drivers record, and a few more. Wikipedia lists the general process here. However, recently, several insurance companies have sharpened their risk analysis using GPS evidence. The new type of insurance, called Usage Based Insurance, is described by Wikipedia here. Insured persons or organizations typically pay based on the actual miles driven, combined with identified risk factors for that driver. Usage Based Insurance can potentially save the insured a great amount of premium over traditional risk rating systems.

Other systems use on board telekenitics reporting systems that report g-forces and other vehicle information without GPS location reporting. These factors report a lot about the vehicle driven, and perhaps the driver, but not much about the environment it is being driven in.

Combinations of these systems, together with some outside data on real physical risks of the environment, promise a pinpoint risk assessment system that can allow an insurer to charge no more than the actual risk the insured incurs. Rather than rating an entire town or region for risk, insurers could rate individual intersections and road segments, measure the insureds travel on those road segments and through those intersections, compare the insureds skill at driving (in near real time) and assess the premium.

The problem with usual rating systems- As I drive down the road, I am charged with the risk of the 2 a.m. bartime accidents, the "late to work" rush hour accidents, the noon time "hurry to lunch & back" accidents, the teen "after school rush" accidents, dusk "visibility problem" travel, even if I only drive at 10 a.m and 2 p.m. Even if I only travel residential streets, I could be charged with the risk of interstate highway travel, high volume intersection travel, sporting event travel, and the like. Even though might I travel through quite neighborhoods with little traffic, I could be charged with traveling through downtown, industrial area, or dangerous sections, if any of these are in my rating territory. Although I may only drive short distances relatively rarely, my insurer can only give me a small discount because some drivers might lie about their actual mileage, and the insurer take a risk if it has too small a bottom bracket. In short, a rating territory is (and has to be) quite large, and some drivers bear the costs of risks other drivers are taking. Usage Based Insurance balances and corrects those inequities.

The benefit the using both GPS and telemetry systems: The telemetry tells how the insured driver is driving; the GPS location + geocoded accident data (and the time of day) tell how the other drivers in the same area are driving.

If such systems were combined with real time feedback from the insurer, like a talking copilot to warn of dangerous intersections, or detected speed violations for the road in question, the insured could reduce his own premiums and the roads could be made safer for all. Never before could an insurer take positive actions in real time to reduce risk to the insured, both as public service and as a huge money saver.

Here's how it could work (and may work, as the author hasn't reviewed all the systems involved.) The following is just my opinion of what a GPS/telemetric system is capable of:-
  1. Insurers install, for a price break, GPS units on "study vehicles" in a given territory.
  2. Simultaneously, insurance rating organizations geocode (Wikipedia definition) the accident locations for that territory for a given time span, say, the last ten years. These geocodings include a cronological element, giving the time of day the accident occurred. A final code would indicate the severity of each accident, including whether the parties carried insurance for the loss.
  3. Using the geocoded information, insurers assign a relative risk rating to each street segment and intersection hour by hour. If necessary, data can be analyzed by seasons, as accidents will likely increase during winter or rainy seasons.
  4. When the system is generally deployed, insureds pay standard rates while driving with a GPS & telemetry data analyzers for a time period. This allows the insurer to "calibrate" the system and determine the accuracy of the GPS rating system. Ultimately, what rate to charge in specific situations will be a judgment call-however, that rate can be constantly adjusted by my current driving record, my personal driving risk (assessed by telemetry systems in the car), where I am driving, what time I'm driving, the kind, type, severity and time of accidents that have occurred on my route, and the length of time I'm exposed to those risks (by mileage and/or time.)
  5. Finally, the full system is in place, and the insurer starts charging its insureds by mileage driven or time the vehicle is traveling at a rate based on the factors above.
  6. Picture a drive under Usage Based insurance:
    • Sitting in my garage, my vehicle is still under some risk, say, of fire, so I'm charged a very low rate while garaged. Were my vehicle on the street, the risk might be higher, because of theft and weather threats.
    • I drive out onto the street. My onboard GPS tells the insurer where I am. Either in real-time (as it is happening) or later, depending on if there is a link to cellular phone system/ or the internet, the GPS would constantly update my position. The insurer's computers would correlate this position with accident histories on my street, assign a risk score, and charge a premium for my trip so far.
    • I come to a dangerous intersection- no traffic controls and I must cross four lanes of traffic. My GPS comes with "feedback", and warns me of the danger coming up, and suggests a safer route. (This "feedback" information need not come from the insurer in real time - insurers could send CDs, DVDs, or embed the information in the GPS memory for most "feedback" information where the insured is likely to drive. Insureds driving outside a covered area could get realtime "feedback".) As I drive down the road, my insurer can compare accident types, times of accidents, how much those accidents cost and assess how likely I am to have an accident on this trip (with my driving record, age, and driving habits.).
    • If I'm out in the country, its a beautiful day and a good song comes on the radio, my GPS will alert me that I'm going over the speed limit for this. Of course, it will take note of my slip and charge me a slightly higher premium, but the "feedback" stops me from continuing the risky behavior and having a much more expensive accident. The realtime "feedback" saves me money in the long run, as I'm much less likely to have an accident in the future.
  7. When a new accident actually happens somewhere to some GPS tracked driver (and it will) the GPS record and telemetry will help the insurer quickly determine fault, pay the claim if necessary, or litigate the claim if need be, with confidence. If both cars have GPS and telemetry, the additional information will make the investigation much easier. This is not to say GPS will solve all cases- a car crossing over the center line involves feet and inches, not yards & miles- but GPS & vehicle telemetry will narrow the issues like speed, location and timing, depending on how accurate the GPS is set to report and record. GPS's could record data to two areas-Standard and highly-accurate-rotating-buffer areas. The buffer would record, for instance, 20 seconds of very accurate data, continuously writing over that data, but "dumping" the buffer to permanent memory when high G-force conditions were detected. This would "freeze" the data from an accident situation.

If enough drivers have enough GPS "feedback" over time, they will change their habits, become better drivers, and thus, lower their premiums. Bad drivers, on the other hand, will be located quickly:
  1. Bob Baddriver, after an evening in a bar, gets in his vehicle and starts it up. The GPS notes its 2 a.m., bar time in most places, and a dangerous time of day even for the sober. While the GPS doesn't know Bob Baddriver was in a bar (it could, with enough correlation, but that would be both intrusive and prone to erroneous assumptions - maybe Baddriver is the designated sober driver) it can tell if there were accidents in this area around this time, and start charging an appropriate premium.
  2. Bob Baddriver, it turns out, has been drinking. He speeds. He ignores the feedback. His premiums are shooting higher as he goes. He crosses the center line. Realizing it, he locks up the brakes. He takes a deep breath, and drives home as carefully as possible. However, his insurer has noticed. His premium bill comes the next month. He will either pay for his risky behavior or have his policy canceled.
  3. Leaving the same bar Sammy Goodfella is a designated driver, using Usage Based Insurance. While he pays a little more for driving this time of night, the telemetry notes his anticipation of road hazards and safe driving, and his use of low risk routes. He pays a little more for being the designated driver.
  4. Bill Boring, home in bed, doesn't pay anything to cover the elevated risk of these two drivers.
This kind of analysis can go on for any motor vehicle, train, plane, car, bus, or commercial carrier.

As more drivers go to Usage Based Insurance, the remaining pool of traditional insured drivers will likely be the more risky drivers who want to hide their behavior. Premiums are likely to climb among them, driving more to Usage Based Insurance. Eventually, while standard insurance might be available, it is likely to cost so much that even the risky insureds will go with Usage Based Insurance, and the risk the insurer knows is probably less than the risk of the unknown.

Monday, September 14, 2009

Voluntary GPS tracking for the impulsive?

In our society, there are some individuals who have trouble controlling their impulses to do wrong and violate the law, unless they believe someone is watching them. Surely we've all seen traffic slow down when a police car is present, and the presence of video cameras in department stores surely cut down on shoplifting. I'm not talking about those people who will take whatever they can whenever they can. I'm talking about those who genuinely want to control whatever behavior violates the law, but in weak moments give in to the urge to do the wrongful act, and regret it later, even if they are not caught.

Such individuals, when they are of clear mind, might desire to be GPS tracked to help them curb their behaviors. Knowing someone is (or could be) watching their locational behavior will reinforce their conscience, keep them on the straight and narrow, and help them resist the passing impulse to commit crimes that are really not in their nature.

GPS technology could be set to give them feedback when they are entering a situation that might tempt them. Geofences, that is, electronic fences, could be set up to let them know they are close to an area they should stay out of, or leaving an area they should stay in.

Making GPS technology available to those requesting it for specific urges or problems would be cost effective both for the individuals and for society. The individual would lose their freedom if caught committing a crime. Society in general loses the cost of prosecuting, incarcerating and physically monitoring the individual if a crime occurs. Finally, victims of the crime stand to lose much more in property loss, bodily integrity, emotional agony, or even their lives. Victims costs are impossible to put in dollar terms.

Much like those we allow to civilly commit themselves to mental hospitals, those requesting GPS tracking could "sign themselves in" and out, presumably, or remain under surveillance. Much like the ankle-bracelet surveillance used for convicted or accused criminals, individuals voluntarily GPS tracked would have to allow the unit to be attached in such a way that only authorized personnel could remove it. Otherwise, at the first impulse the person tracked would take the GPS tracker off and commit the act. Removal would require a process, although voluntary, that would take long enough to allow the person to get through a period of bad urges without violating.

Here are some possible applications:
  1. Alcoholics could be tracked to help them keep away from drinking establishments, liquor store sales, and the like. Geofences could be programed around places that serve and sell alcohol so the person tracked would be alerted he or she was about to enter a dangerous area that might test their will power. The person tracked might even allow release of their tracks, in real time, to their AA sponsor, so an alerted sponsor might intervene in the behavior.
  2. Those who opt for criminal diversion programs may chose to allow themselves to be tracked. For instance, first offense DWI defendants might sign up to prevent that second DWI. (Insurers might insist on this as a condition of continued insurance.) This group might also use the "Geofencing" described above, along with the feedback provisions.
  3. Those under Occupational Licenses might sign up, so they know they can't deviate from the terms of their license. Loss of an occupational license could mean the loss of a job, and livelihood, so keeping on track can be very important for these individuals.
  4. Ex-convicts who are no longer under supervision might choose tracking to keep them away from other known criminals and ex-convicts-to help keep them from falling back into old habits, and keep them out of jail. "Geofencing" from known areas, addresses of other ex-convicts, and high crime areas could help them keep on the right track.
  5. Those accused of crime may want to be tracked to prove they couldn't have committed further crimes they might be accused of (such as serial crimes, like assaults or killings.)
  6. Those who have not yet committed crimes against children, but fear they might, could be Geofenced from areas where children congregate, like schools and parks.
  7. Traffic offenders - some folks can't help having a heavy foot, especially when no one is looking. Knowing GPS tracking is always looking will help them control and change their habits. Tickets not only threaten their continued ability to drive, it raises their insurance premiums, and makes them more likely to hurt or kill themselves or others. Here geofencing might be "keyed" to speed limits and perhaps, G-forces in the vehicle could be recorded.
Geofencing might be keyed to both location and/or time. In other words, it might be OK to drive by a bar, but if the GPS detects continued presence at the bar for 5 minutes or more, it will trigger a feedback alarm.

If the system is properly automated, the Geofencing can alarm whoever is tasked with "watching" those who are voluntarily tracked. The tracks, however, would be retained and archived (which would be explained to the voluntarily tracked) so if any laws were violated by the individual, the track would permanently provide evidence of the voluntarily tracked persons whereabouts at the times in question.

Even with a well administered system, some of the voluntarily tracked will give in to impulses. GPS tracking, then, will provide swift prosecution, solid evidence, and hopefully incarcerate those who only commit one crime rather than a string of crimes. Such a system would give justice to the victims, and lessen their numbers.

Friday, September 4, 2009

Should the Existence of "Spoofing" or "Jamming" GPS signals render GPS generated evidence inadmissable?

I've reviewed a couple of articles on the Internet that argue that GPS evidence should not be admissible in court. Some criticize GPS tracking as not accurate enough, which is surprising, as New York's highest court excluded warrantless GPS tracking evidence because of its far too accurate abilities. This post, however, will analyze whether "Spoofing" or "Jamming" technologies, by their very existence, so taint any possible GPS evidence generation as to render GPS evidence generally unaccepted and unreliable, and thus excluded under the Frye standard. (Wikipedia explanation).

Professor Susan Brenner did an excellent description of "Spoofing" and "Jamming" in her CYB3CRIM3 Blog. I see no reason to reinvent the wheel, so thanks to her, I will forgo an explanation.

In our society, many things can be forged, manipulated, altered or used without proper authority. U.S. Currency can be counterfeited, yet we all use it every day, usually without looking at it twice. Photos, now usually generated either digitally or from magnetic signal (on videotape) can be digitally retouched, making it difficult to know what the original looked like. Audio recordings can be sliced, spliced and diced to put words in someone's mouth. Documents can be scanned and signatures transferred that rival the original, thus rendering the documents complete and utter forgeries. Video tapes, likewise, can be doctored to make the impossible seem possible.

Yet, despite the existence of technologies that make it harder and harder to know what is "real," our court system every day accepts into evidence as real both currency, photographs, audio statements and recordings, signed documents and videotapes. While parties have the right to challenge the authenticity of evidence, no court I know of has ever barred evidence just because a technology exists that someone might use to tinker with or outright falsify the evidence. Likewise, I don't believe any court should exclude GPS evidence simply because someone somewhere has the capability of tampering with that evidence.

To be clear, there are four methods of "tampering" with GPS evidence I know of 1) "Jamming" GPS signals (thus blinding the GPS to location completely 2) "Spoofing" GPS- externally sending signals to the GPS reciever to make it think it is in a different location than it actually is 3) Uploading a false GPS track into a totally accurate GPS (which I describe in a blog post here.) 4) Tampering with the GPS evidence after it has been downloaded (which would be evident if the parties follow appropriate downloading procedures, and built a chain of custody of the raw GPS data.)

"Jamming" is very easily dealt with- It can't bar admission of GPS generated evidence, as, by definition, "Jamming" blinds the receiver. Now, unless the "Jammer" is mobile, and following the GPS tracked vehicle, it is likely only to block a portion of the GPS track. GPS tracks, however, are severable-that is, each trackpoint is constructed independent of the previous trackpoint, so each trackpoint constitutes admissable evidence without depending on the other trackpoints before it or trackpoints following it.
Therefore, if a court is presented with a "partial" track, individual track points, if relevant, are admissible to prove whatever the proponent is attempting to prove. Accordingly, "jamming" only creates an information vacuum for the period of time it is going on, and does not effect the veracity of the rest of the trackpoints, and therefore, the rest of the track.

Jamming is analogous to blinding a camera with a bright light to something the camera should be able to see, but can't through the light. We don't discard the rest of the photo because one portion is washed out. Nor does the washed out part lack information-we just can't see it. But the washed out part does not "contaminate" the rest of the photo.

Uploading a false track is like loading an official camera with film taken from a different camera, that appears to be real. Careful examination of GPS tracks will disclose problems, and careful "chains of evidence" will ensure the veracity of GPS track evidence.

Tampering with downloaded GPS evidence is like retouching a photograph after it has left the camera. This, too, can be prevented by preserving the raw data in a non-changeable form, like burning to a CD, and carefully protecting the chain of evidence that data goes through.

Attorneys should, and will, examine those who handle and process GPS evidence to make sure these evidenciary foundations have been fulfulled before GPS tracks are admitted. Doing so ensures the accuracy and credibility of the GPS evidence presented.

Finally, "spoofing" is the most troublesome technology. "Spoofing" a GPS is like setting a false scene for an official camera to shoot, but the scene appears real. The camera works, parts of the scene appear real, but something is false as part of the scene. Accordingly, where the jammer simply leaves a vaccum of information, the spoofer gives false information.

Fortunately, spoofing a GPS that would be admitted to court would be incredibly complicated. First of all, either the subject of the GPS tracking would have to know that he was being tracked to be involved in a "spoofing" in the first place, if he intended to use the spoofed track on his own behalf. The only GPS targets that know they are being tracked are criminals (or accused criminals) wearing GPS bracelets. While there is a possible scenario that the criminal spoofs the bracelet into thinking he is stationary when he is out committing a crime, the criminal would have to have good expertise, and good luck.

"Spoofing" has one other telltale characteristic- because the GPS satellites broadcast to ALL GPS recievers, and "spoofing" gear would have to overcome those signals to "spoof" a position, thus transmitting the "spoofed" signal to all the GPS recievers in the area, not just the target GPS. Where such tracks can be located and compared, and the GPS users interviewed, spoofing will either be proven, or disproven.

"Spoofing" an immobile GPS to make it look mobile could be easy, but in real life, "created" movements may become shockingly apparent when, for instance, a GPS tracked accused criminal crosses a river where there is no bridge, the GPS did not move with the actual current, and where the GPS isn't waterproof. Likewise, if the GPS travels over high fences, through secured areas or over cliffs, it will be suspect. Finally, a GPS attached to vehicle that routinely follows paved roads will be suspect when it starts to travel through cornfields and through swamps. While "spoofing" is possible in theory, "spoofers" may find that, like currency counterfeiters, the details are what trip them up.

"Spoofing" a mobile GPS would be quite difficult, given that the distances between the transmitting "spoofer" vehicle and the GPS tracked vehicle would vary, so would the strength of the signal, and real signals could leak through. Also, the "spoofing" vehicle would have to know where it was at all times to correctly transmit spoofing data that "makes sense" in the real world. How can it do that with a spoofed GPS reciever?

Because the slim likelyhood of successfully "spoofing" a GPS receiver without having it detected in the track, I would conclude spoofing, as a technology, is not a reason to either doubt GPS tracks or exclude them from evidence.

Finally, because both "Jamming" and "Spoofing" depend on transmitting data over the airways, anyone who attempts to either "spoof" or "jam" risks location and prosecution themselves. Because the equipment is specific, because many agencies can sample the airwaves, and because GPS signals have a national security dimension, it is unlikely in the extreme many would expose themselves by trying to jam or spoof GPS signals.