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Comment by Lawtonfogle | Hacker News Reader

>They're giving over the information to a third party, which usually destroys any 4th amendment rights.

Same reason that there is no need for a warrant to collect phone calls since you are handing data over to the phone companies to carry between you and the other party(ies). Also the same reason the government can shift through your mail, since the items are in the possession of a third party (you likely gave the items to the government itself).

To me this makes as much sense as the argument that since a plane carrying people can fly over you, it is perfectly reasonable to put a blimp with an extremely high zoom camera on that spies on your home constantly, detecting not just visible light, but also infrared. Also, since when you talk things vibrate, and since it is possible to view those vibrations though a window, I'm actually broadcasting my speech to the public and thus don't have any expectation of privacy.

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These issues have actually been litigated in court. The broad consensus is that yes, the police can use a surveillance plane can take pictures of you without first obtaining a warrant (Florida v. Riley), but no, they can't use infrared camera to look inside your home without a warrant. (Kyllo v. United States)

None of these cases are really analogous to the Tor case. Generally speaking, you have no reasonable expectation of privacy that information that you voluntarily provide to a third party will be kept confidential. This is why the police doesn't need a warrant to get your phone records or to obtain your IP address.

You bring up mail, which is an interesting case. Conents of a sealed mail IS protected by the Fourth Amendment - it's just that the government usually relies on the "exigent circumstances" exception to the warrant requirement (basically, showing that there is probable cause to search the mail but that there is no time to obtain a warrant). The government can't just mass-open all sealed mails and look at their contents.

Just to add a bit more information, the Kyllo v. US case was decided based on what a person would reasonably expect a member of the public to own.

Many people have planes that fly about, drones or whatnot. So you could expect random members of the public to have ways of taking arial pictures of your house. Therefore those do not violate your right to privacy.

It's very unlikely for a member of the public to own a helicopter with an infrared camera, so using it without a warrant is a violation of privacy.

The basic example used by a court is binoculars. Most people have access to binoculars, and own them. So if you do something next to your window, police can totally look through your windows with binoculars and act on the information.

A helicopter with an infrared camera costs about $100.

I believe he is referring to a thermal imaging camera, which can see heat sources. They're still somewhat an expensive specialty item. The police used to use them to look for people growing marijuana in their attics, but higher courts now say that would require a warrant.

He may be, but over the last few years some models have come out with much lower prices: http://appleinsider.com/articles/14/11/23/review-flir-one-an...

I wouldn't be surprised if there are usable thermal imaging sensors out there for $100.

It's probably worth noting that Kyllo is one of the cases where the recently deceased Justice Scalia's "conservatism" produced a decision favorable to privacy advocates:

  We have said that the Fourth Amendment draws "a firm line 
  at the entrance to the house," Payton, 445 U. S., at 590. 
  That line, we think, must be not only firm but also bright— 
  which requires clear specification of those methods of 
  surveillance that require a warrant. While it is certainly 
  possible to conclude from the videotape of the thermal 
  imaging that occurred in this case that no "significant" 
  compromise of the homeowner's privacy has occurred, we must 
  take the long view, from the original meaning of the Fourth 
  Amendment forward.

    "The Fourth Amendment is to be construed in the light of 
    what was deemed an unreasonable search and seizure when 
    it was adopted, and in a manner which will conserve 
    public interests as well as the interests and rights of 
    individual citizens." Carroll v. United States, 267 U. S. 
    132, 149 (1925).

  Where, as here, the Government uses a device that is not in   
  general public use, to explore details of the home that 
  would previously have been unknowable without physical 
  intrusion, the surveillance is a "search" and is 
  presumptively unreasonable without a warrant.

https://scholar.google.com/scholar_case?case=158400455911157...

Note that this is only talking constitutionally. The government is free to pass laws that disallow such gathering, or simply not pass laws that allow it.

IIRC collecting mail is not in fact legal without a warrant, and only photographing the outside (which anyone who handles it can see) is allowed.

I do think the fact that any member of the public can collect data legally means the government should be able to as well.

> To me this makes as much sense as the argument that since a plane carrying people can fly over you, it is perfectly reasonable to put a blimp with an extremely high zoom camera on that spies on your home constantly, detecting not just visible light, but also infrared. Also, since when you talk things vibrate, and since it is possible to view those vibrations though a window, I'm actually broadcasting my speech to the public and thus don't have any expectation of privacy.

I doubt anyone is making that argument; in Kyllo v. United States the Supreme Court held that infrared cameras constituted an unreasonable search. Recording vibrations would also likely fall in the same category.

Police spying on you from a blimp is fairly unlikely, since it would be fairly conspicuous, not to mention expensive. Far more likely they just stick a camera on a utility pole as in the recent United States v. Houston, what you're most likely alluding to. The Sixth Circuit did uphold that tactic, but the law is far from settled there.

>Police spying on you from a blimp is fairly unlikely, since it would be fairly conspicuous, not to mention expensive. The Army is actually doing this: https://theintercept.com/2014/12/17/billion-dollar-surveilla...

The scary thing about those blimps is that we used exactly those in our various warzones. Look for them in pictures of Kabul or Baghdad while Americans were there. I used to joke to buddies in my unit that it was even the same contractor sitting in the trailer where the blimp is anchored, watching the video.

Looks pretty conspicuous to me, and also extremely unlikely to be used for sustained surveillance of a person. Also sounds likely to be discontinued when funding runs out. A load of hot air, in other words.

I recognize the similarity between phone calls and Tor; however, I too think there is a difference in the expectation of privacy.

I like your analogy with aerial surveillance, but partially because I think you are wrong. It is my understanding that aerial views available to the public, such as those available to a commercial helicopter, do not require a warrant. However, if the police go beyond public capabilities with high zoom cameras it may require a warrant. Similarly, if the state goes beyond the capabilities of the public in obtaining my IP address, they should require a warrant. The question then becomes, "Does the CMU project constitute knowledge generally available to the public?" I would argue the negative, but I could see it answered either way.

It doesn't need to be available to the public, only available to third parties. There are a finite number of people (either 3 or 6) that together have all the data needed to identify the user.

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