That's an issue that's arising in many forms recently, and I'm not sure the law has sorted out what to do about it.
The gut feeling, which I share, is that there's a qualitative difference between a few targeted observations and pervasive surveillance. But the law has traditionally not included a numerical aspect in 4th-amendment analyses. Either the police need a warrant to fly a helicopter over a city and photograph it, or they don't, regardless of whether they're flying one or a hundred. Saying that something would require a warrant if done very frequently but not if done occasionally would require a either a novel approach to the 4th amendment, or a new law passed by Congress specifying a new policy.
Two bits of 4th amendment law do point towards development of a new doctrine, but I'm not sure very strongly:
1. In United States v. Knotts (1983), the defendant argued that allowing the government to electronically track a vehicle without a warrant raised the spectre of the government being able to pervasively track all movements. The court dismissed that concern by writing: [Defendant] expresses the generalized view that the result of the holding sought by the Government would be that "twenty-four hour surveillance of any citizen of this country will be possible, without judicial knowledge or supervision." But the fact is that the reality hardly suggests abuse; if such dragnet-type law enforcement practices as respondent envisions should eventually occur, there will be time enough then to determine whether different constitutional principles may be applicable.
It's a bit of a confusing comment, though, because it doesn't explain the basis for treating "dragnet-type" uses of GPS tracking differently from scattered uses, from a 4th-amendment perspective. My guess is that Rehnquist just wanted to dismiss the defendant's dystopian hypothetical by saying it's not happening now and if it happens later, well we'll deal with it later.
2. One lower court has introduced a "mosaic theory" of the fourth amendment by which things that individually don't count as "searches" for 4th-amendment purposes could constitute a search when aggregated. Here's an article on that: http://scholarship.law.gwu.edu/cgi/viewcontent.cgi?article=1...
I'm not a lawyer, but I could see an argument being made for a "numerical aspect" to privacy protections. The idea of a reasonable expectation of privacy as a standard seems well supported, and I think it could apply to this situation.
Certainly the police COULD track me when I'm out in public, but my expectation is that they won't unless they have a valid reason for doing so. So while I may not have an explicit legal protection against being tracked in public as an individual, I have an expectation that I'm not being tracked unless I'm the subject of an investigation.
I suppose this is less of a numerical aspect as it is a reasonable expectation factor for the majority of people who would be tracked with pervasive drone surveillance. People just going about their business don't expect to be randomly tracked by the FBI, but most people would probably expect to be tracked if they were specifically being investigated.
But like I said, I'm not a lawyer, so it might be impractical for the law to work that way. If so, then maybe a change in the law will be necessary if it becomes practical to engage in pervasive drone surveillance and it turns out that's what the FBI ends up doing.
Kind of interestingly, the government actually does use that mosaic theory elsewhere, when dealing with 'national security information'.
There is a concept that there are types of information which are unclassified individually, but which can 'become classified' if joined as part of a compilation.
Of course the law is not exactly the same as information security but I don't see why the government should use mosaics in one area and then claim they can't be used for similar concepts elsewhere.
The gut feeling, which I share, is that there's a qualitative difference between a few targeted observations and pervasive surveillance. But the law has traditionally not included a numerical aspect in 4th-amendment analyses. Either the police need a warrant to fly a helicopter over a city and photograph it, or they don't, regardless of whether they're flying one or a hundred. Saying that something would require a warrant if done very frequently but not if done occasionally would require a either a novel approach to the 4th amendment, or a new law passed by Congress specifying a new policy.
Two bits of 4th amendment law do point towards development of a new doctrine, but I'm not sure very strongly:
1. In United States v. Knotts (1983), the defendant argued that allowing the government to electronically track a vehicle without a warrant raised the spectre of the government being able to pervasively track all movements. The court dismissed that concern by writing: [Defendant] expresses the generalized view that the result of the holding sought by the Government would be that "twenty-four hour surveillance of any citizen of this country will be possible, without judicial knowledge or supervision." But the fact is that the reality hardly suggests abuse; if such dragnet-type law enforcement practices as respondent envisions should eventually occur, there will be time enough then to determine whether different constitutional principles may be applicable.
It's a bit of a confusing comment, though, because it doesn't explain the basis for treating "dragnet-type" uses of GPS tracking differently from scattered uses, from a 4th-amendment perspective. My guess is that Rehnquist just wanted to dismiss the defendant's dystopian hypothetical by saying it's not happening now and if it happens later, well we'll deal with it later.
2. One lower court has introduced a "mosaic theory" of the fourth amendment by which things that individually don't count as "searches" for 4th-amendment purposes could constitute a search when aggregated. Here's an article on that: http://scholarship.law.gwu.edu/cgi/viewcontent.cgi?article=1...