I'll address a couple of points you missed (edit: but which you have addressed elsewhere in the thread - just wanted to gather it up in place rather than post 10 times):-
a. If putting a GPS tracker on my car* involves venturing onto my driveway during the night, then you're intruding on the curtilage of my dwelling. The fact that the mail carrier or meter reader is allowed to do so does not mean that I grant the police a free invite onto the easily accessible parts of my property. This is the basic issue that the Supreme Court will take up today.
* not that I actually have a car - a cunning anti-surveillance measure, if I say so myself
b. Even if I park my car on the street, shouldn't the police have to deal with economic scarcity like everyone else, and prioritize whether or not I am worthy of investigation? If technology as a matter of convenience is acceptable grounds for carrying out surveillance, why not require all cars to be fitted with GPS trackers that record their position and can be read out wirelessly by any passing cop who thinks he recognizes your car from a recent tip? If we don't want to force people to buy GPS devices, then why not make such GPS data automatically searchable? Google Latitude records all my movements, should the police have access to that without a warrant for reasons of convenience?
c. In any of these cases, should we mandate that the information be public? After all, if a crime is sufficiently interesting, the media will sue for access to all evidence or to broadcast the court proceedings on first amendment grounds (spurious ones if you ask me; I've soured on TV trials). Since the evidence will become public anyway, what interest does the individual have in keeping it private once the state has decided to inspect it? No jurisprudence says that you have any property interest in your privacy, and it's not hard to construct an argument for any given search being reasonable. I've seen the presence of raindrops on a moving vehicle at 3am offered and accepted as reasonable grounds for a search (which correct intuition helped to catch a murderer fleeing the scene of a crime, as it turned out).
d. If almost any search is reasonable and can become a matter of public record by default, is there not an argument that possession of a GPS device in a car or phone that is deliberately turned off, disabled, or left behind by the user constitutes circumstantial evidence of intent in criminal or even tort cases? As you know, the threshold for establishing intent or knowledge in criminal cases can be quite low if it's not the sole fact in question, and it's lower again in civil litigation. If I can demonstrate a pattern of GPS use on your part that is temporarily interrupted during a period overlapping the commission of a crime that was reasonably accessible from your last recorded location, isn't there a basis for suspecting that you wished to conceal your movements?
e. Even if a warrant is required for me to get hold of your phone records or gain access to the contents of your phone, doesn't the fact that I could snoop your phone use over your shoulder whenever you pull it out in public compromise any expectation of privacy that you have when operating your phone in public? In other words, if I approach you while using your phone and suddenly order you to hand it over for inspection on the grounds that I saw something which appeared suspicious to me on the screen, are you entitled to lock your phone by hitting the power button? After all, your phone was open to the world (in plain view), and that's why I noticed something suspicious about it. Your locking of the device would then seem to constitute interference with a lawful search...
Sure, I'm playing slippery-slope here, but these are all cognizable arguments and I have heard as much and more from various conservatives and police officers over the years. I'm rather conservative myself where jurisprudence is concerned, but GPS tracking strikes me as an active rather than a passive sort of surveillance, not least because it necessarily involves interference with property or person to plant the tracking device.
I think you missed the most important point. GPS data is associated with my car, but there is not guarantee that I am the one opperating the car. Manual police surveillance would (hopefully) notice this. Furthermore, it makes planting false evidence rediculously easy. Some nasty cop (or civillian) could simply transfer the GPS to another vehicle, violate some crimes with it, then transfer it back to the original vehicle.
Without controls preventing these sorts of abuses---and I suspect such controls would be impossible to implement in practice---GPS data would do more harm than good.
True, but you could make the same challenges to human surveillance in many cases, or that of traffic cameras at red lights (with some success, it must be said). I'm trying to focus on the second-order effects that could ensue if I accepted Tom's legal argument at face value.
(a) I don't think it's reasonable for LEOs to invade my driveway, garage, &c to install telemetry devices, just like I would have a problem with getting tickets for having expired tags if my car was pulled all the way into my driveway (which, at least here, the police can't do).
(b) What we're dealing with here is the balance of conflicting interests. What I see is a scale, from "every car is tracked" through "many cars are tracked" to "very few cars are tracked" (though, honestly, I think we all know that proportionally very few cars are going to be tracked with manually-attached FBI telemetry devices). What I'm saying, and the answer to your "why?" question here, is that the state's interests at this point on the scale are more compelling than the individual interests.†
(c) Why is the information we're talking about from telemetry devices any different from dash-cam videos from tail cars, or from pen registers monitoring phone lines, or...? I don't see this as germane. The answer? No, I don't think information collected by law enforcement agencies during investigations should be made public.
(d) Here you've lost me completely. Almost any search is reasonable? Strong disagree!, as they say on Wikipedia. I think fewer searches should be reasonable, in any event, but this isn't a "search", any more than the smoldering one-hitter you leave on the empty passenger seat in your car is "searched" when a cop spots it after ticketing you for weaving in between lanes. Is there an argument that disabling GPS telemetry is evidence of criminal intent? Of course not, no more than closing your shades is evidence of criminal intent when the police are surveilling your house, or shredding documents is intent when the police are collecting your trash.
(e) The difference between a phone conversation and the presence of your vehicle on a public street is the difference between an almost total "reasonable expectation of privacy" and an almost nonexistent "reasonable expectation of privacy". I don't know whether you're arguing this point or not; it may be that I have to agree with the premise that "every search is reasonable" to agree with this point.
† Other people on HN will contend that we should make no concessions against individual interests at all, because, America. But we both know that virtually every individual interest we have has been hardened by decades and decades of tests of the state's legitimate interests vs. individual interests, so that for instance the passenger compartment of my car can be searched incident to an arrest but no the trunk &c &c
a. If putting a GPS tracker on my car* involves venturing onto my driveway during the night, then you're intruding on the curtilage of my dwelling. The fact that the mail carrier or meter reader is allowed to do so does not mean that I grant the police a free invite onto the easily accessible parts of my property. This is the basic issue that the Supreme Court will take up today.
* not that I actually have a car - a cunning anti-surveillance measure, if I say so myself
b. Even if I park my car on the street, shouldn't the police have to deal with economic scarcity like everyone else, and prioritize whether or not I am worthy of investigation? If technology as a matter of convenience is acceptable grounds for carrying out surveillance, why not require all cars to be fitted with GPS trackers that record their position and can be read out wirelessly by any passing cop who thinks he recognizes your car from a recent tip? If we don't want to force people to buy GPS devices, then why not make such GPS data automatically searchable? Google Latitude records all my movements, should the police have access to that without a warrant for reasons of convenience?
c. In any of these cases, should we mandate that the information be public? After all, if a crime is sufficiently interesting, the media will sue for access to all evidence or to broadcast the court proceedings on first amendment grounds (spurious ones if you ask me; I've soured on TV trials). Since the evidence will become public anyway, what interest does the individual have in keeping it private once the state has decided to inspect it? No jurisprudence says that you have any property interest in your privacy, and it's not hard to construct an argument for any given search being reasonable. I've seen the presence of raindrops on a moving vehicle at 3am offered and accepted as reasonable grounds for a search (which correct intuition helped to catch a murderer fleeing the scene of a crime, as it turned out).
d. If almost any search is reasonable and can become a matter of public record by default, is there not an argument that possession of a GPS device in a car or phone that is deliberately turned off, disabled, or left behind by the user constitutes circumstantial evidence of intent in criminal or even tort cases? As you know, the threshold for establishing intent or knowledge in criminal cases can be quite low if it's not the sole fact in question, and it's lower again in civil litigation. If I can demonstrate a pattern of GPS use on your part that is temporarily interrupted during a period overlapping the commission of a crime that was reasonably accessible from your last recorded location, isn't there a basis for suspecting that you wished to conceal your movements?
e. Even if a warrant is required for me to get hold of your phone records or gain access to the contents of your phone, doesn't the fact that I could snoop your phone use over your shoulder whenever you pull it out in public compromise any expectation of privacy that you have when operating your phone in public? In other words, if I approach you while using your phone and suddenly order you to hand it over for inspection on the grounds that I saw something which appeared suspicious to me on the screen, are you entitled to lock your phone by hitting the power button? After all, your phone was open to the world (in plain view), and that's why I noticed something suspicious about it. Your locking of the device would then seem to constitute interference with a lawful search...
Sure, I'm playing slippery-slope here, but these are all cognizable arguments and I have heard as much and more from various conservatives and police officers over the years. I'm rather conservative myself where jurisprudence is concerned, but GPS tracking strikes me as an active rather than a passive sort of surveillance, not least because it necessarily involves interference with property or person to plant the tracking device.