Tuesday, October 18, 2011

GPS Evidence: Pandemic prevention-GPS phone and Locational Evidence could Lead the Search for The Index Patient

Imagine a traveler on a busy Chicago train platform collapses. He is taken for medical help, and first responders quickly realize he has fallen ill with a fast moving highly transmissible virus. First and foremost, the first responders must locate both the travelers contacts by establishing his path of travel, and then test and isolate those contacts as soon as possible.

In the past, such a task would have been insurmountable, for certain courses of travel. Investigators would have to rely on questioning the traveler, which might not be possible if symptoms are too far advanced. Imagine our traveler is comatose, has no ID on him (stolen as he was feeling more poorly), and has a "cloned" phone with no personal information, other than the number. However, it does have GPS tracking capability.

Now, however, for certain types of travel, there is a better way. Most of us carry a locational device everywhere we go. Our cell phone. Using either GPS data or cell transmission triangulation technology, investigators can backtrack tower by tower, or using a GPS track, to determine where a traveler was at a certain time. Compared with possible modes of travel (train, car, plane) available in an area, investigators can surmise both which train the traveler was on, and when the traveler was on it.

OK, so in a couple of hours investigators know the route. However, how can that help them isolate all the people the traveler had contact with - or help locate where he caught the virus?

Two ways. First, the traveler's cell phone is unique, and will act as a way to pick it out from all other cell phones that passed through those locations. Investigators can follow back in time while that number moved backwards, until it finally stops moving backwards and stays stable for some time. That location, most likely, will be the traveler's "home," or something close enough to it that the traveler stayed there long enough to get more information about the traveler. Second, the traveler's number is surrounded by other numbers-numbers representing people he could have been in contact with, who could be infected, or could have given him the infection without knowing it.

How will investigators be able to get this cell phone information? Its private, right? Yes, it is, by Federal Law. However, under the right health crisis, hopefully the investigators can get a quick court order to disclose the information, if they can show how it will help them stop the virus spreading. The Constitution should not be a suicide pact (paraphrasing Justice Jackson in Terminiello v. City of Chicago, 337 U.S. 1 (1949)). With access to numbers of those likely to be close to the traveler, investigators can then broadcast to those phone, and those phones only, pictures of the traveler, contact numbers if the phone owners have specific symptoms, and precautions to take to prevent disease spread. Investigators can also physically locate the current realtime location those who were close to determine who, and when, was likely the source of the traveler's infection, and, if necessary, find and quarantine them. As positive cases are discovered, the whole process starts over again, with each case, until all are "run to ground."

Investigators will be able, with such a system, to determine that a flock of numbers were headed 60 miles an hour down a rail track right where a specific train would have been running, and infer those "numbers" belonged to people on the train. Of course, since people board and exit a train, all those boarding and exiting would also have to be tracked.

At some point, investigators will find someone infected before the traveler, and this person will have to be backtracked, by cell phone, if necessary, until they come to the index case, patient zero. At this point, they should have a handle on the means of transmission and source, necessary to prevent further outbreak.

While conventional methods may work to quell an outbreak, a targeted cell phone, locational based and GPS directed investigation will take hours or days less, and save more lives in the outcome.


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