The 4th Amendment - and specifically its warrant requirement - is often misunderstood to be about protecting individuals from government searches. Warrants will generally be granted, and the search of any particular individual is going to happen if the government wants it to. The protection for individuals happens later when evidence that was improperly obtained could be ruled inadmissible by the exclusionary rule. The search will probably happen, but the results of that search may not apply in court.

The warrant requirement is an attempt to protect society in general against threats like the writs of assistance that were imposed upon the colonies. From the perspective of an individual search, obtaining a warrant is a trivial speed bump.

If you wanted to search an entire city, on the other hand, those speed bumps serve as a rate limiter. It is just not possible for even a large, corrupt, overfunded and overstaffed police force to "particularly describe" what each search is for and get each one rubber stamped by a judge. Our police and judicial systems have many inefficiencies like this by design.

In modern times, we probably need to extend this idea to the public space, to impose some kind of new rate-limiter. It doesn't matter if the government can ask for occasional data, but allowing a continual collection and a permanent database is the kind of "general warrant" style collection that we need to prevent. The problem is when data is the aggregated, so we need to strongly rate limit the collection so there is no data to aggregate.

By the way - while license plate data is bad enough, I hope everybody remembers that they are making a detailed map of their movements and a graph of probably relationships when they carry a cell phone thanks to COTRAVELER. That slide from the Snowden archive didn't get a lot of press, but it is probably one of the more easily abused programs out of all of the recent revelations.

Yes, but at the time the Constitution was written warrants were a requirements for a search. If a British officer showed up on your property and demanded to search it without a warrant you could literally shoot him.

This led to the issuance of "general warrants," allowing British officers to search entire houses and estates. The Fourth Amendment was a direct reaction to that, which is enshrined in the language "no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."

But you conveniently left out the most important part: the rationale at the beginning of the Amendment: "The right of the people to be secure in their persons, houses, papers, and effects,[a] against unreasonable searches and seizures, shall not be violated"

The whole purpose of the Amendment was to protect individuals from government searches. The text says so right on its face: "The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated..."

The exclusionary rule or "fruit of the poisonous tree" doctrine, with which you seem to be confusing the Amendment itself, is a twentieth century invention of the Warren court.

By the time of the Constitution, a British officer demanding to search your premises had more problems than whether or not they had a warrant.

Its true that by the time of the Constitution, most states required particular warrants -- these requirements were adopted in the Constitutions many states adopted when the declared independence. General "writs of assistance", which were transferrable blank checks issued to particular officers that lasted for the entire length of a monarch's reign (and for 6 months thereafter!) were permitted prior to that (perceived abuse of these by the British customs authorities was, in fact, one of the major source of tension leading to the revolution.)

But yes, the purpose of the Amendment was to protect individuals.

> The exclusionary rule or "fruit of the poisonous tree" doctrine, with which you seem to be confusing the Amendment itself, is a twentieth century invention of the Warren court.

Its worth noting that before the exclusionary rule, there was no remedy for most violations of the Fourth Amendment. The exclusionary rule doesn't substitute for the protection of the Amendment, it gives them some (though limited) teeth.

>The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

He/She is exactly right – the fourth amendment is highly relevant even after a search has taken place.

This is true but it protects against "unreasonable" searches. I'd much rather have my house be searched after a judge deems it necessary, rather than there being no accountability or oversight, and the police deciding on their own that they want to. Other than that, I agree.

It prohibits unreasonable searches. Whether it protects against them depends on the effectiveness with which its prohibition is enforced. Unfortunately, enforcement through the courts has been effectively limited to the exclusionary rule, which is perhaps a reasonably sufficient remedy against unreasonable searches for the purposes of criminal prosecution [0], but is completely useless against unreasonable searches for other purposes.

[0] though perhaps not, there's all kinds of exploitable limitations to the exclusionary rule even in the criminal domain.

The occasional flyover to look for narcotics operations may be permissible, because there is no expectation of privacy in a public space.

But monitoring an entire city with aerostats and quadrotors, or storing the location information of the entire population through license plate readers, while justifiable under the same legal rationale, is a completely different situation.

From a practical reading of the Constitution, it is clearly violative of the Fourth Amendment.

The issue here is: is it right for the police to be able to perform physical surveillance of an individual? It's a yes or no question, regardless of what use the police make of technology. If you think the police shouldn't be able to follow you around to see what meetings you go to, which they can do now without a warrant, then it shouldn't matter if they do it with their feet or by automatically capturing and recording license plate numbers.

Technical capability doesn't alter the definition of right and wrong. This is why we should think through laws and rules carefully, so that they apply not only to the present, but to how things might be in the future. If it turns out that we need new laws, then there's a process for changing them. But I don't think that we should let the technical trends of the moment alter how we view our basic principles.

And it creates problems that just weren't problems when the law was written. Maybe the laws should have been written more carefully but that's a rather idealistic position. That laws regarding control of personal airspace over my house didn't anticipate the widespread use of consumer drones is pretty understandable. Ditto lots of laws regarding regulation of weaponry, etc.

In this case, we've been seeing nominally public info become more readily available for a while now. There are good reasons most public information (deeds, etc.) are public. But that used to mean someone had to have a good reason to look at them because they'd have to trudge down to the county clerk's office. And maybe the town clerk's office. And then some other clerk's office. Now it's all aggregated in one place at the touch of a button. The good reasons those records were public in the first place haven't gone away. But technology has fundamentally changed the scope of how that information can be used.

However, throwing a huge net and catching everybody, then later filtering out what you want is a totally different process. It is leading to a process where guilt is often presumed and you filter out those later who aren't guilty of something. These types of processes continue to reverse innocent until proven guilty to guilty until proven innocent.

In terms of reducing the scale to a single person (which I think has problems, but nonetheless), I don't think most people would classify police following someone around to see what religious ceremonies, political meetings, and protests he or she goes to is acceptable, however we don't worry as profoundly about this because police simply don't have the manpower to do it. License plate readers change this, making mass monitoring of individuals feasible.

Not to mention scale... having a few thousand police officers patrolling a city is acceptable... Having several battalions of a hundred thousand soldiers, not so much.

Do remember, that before this technological advance there was a decided cost to surveil someone. A unit or several would have to be placed on detail to monitor one person. That cost has gone down substantially and as a result, what might have seemed innocuous before has taken on a completely different character. We, as a country, tolerated many injustices towards minority groups because it didn't impact us. Now, we are faced with an impact that is total. It doesn't change the question but does reframe the question.

Yes, this is something the police should be able to do. But that is not the question at hand, is it? This is about performing physical surveillance on all individuals, all the time. Those are two very different things!

And if you tell anyone about which city and which company, they threaten you with legal repercussions.

...This creates new implications for privacy. In the past the government simply didn't have the resources to know exactly what religious ceremonies, political meetings, protests every American was going to. Now they do."