PRISM

[Lamplighter]

...along that line, here is a story about bank robbers, the FBI, and "tower dumps"

http://arstechnica.com/tech-policy/2...hy-it-matters/
Ars Technica
Nate Anderson
8/29/13

How “cell tower dumps” caught the High Country Bandits—and why it matters
Fishing expeditions can pay dividends—but do they need a warrant?

On February 18, 2010, the FBI field office in Denver issued a "wanted" notice
for two men known as "the High Country Bandits"—a rather grandiose name
for a pair of middle-aged white men who had been knocking down rural banks
in northern Arizona and Colorado, grabbing a few thousand dollars
from a teller's cash drawer and sometimes escaping on a stolen all-terrain vehicle (ATV).
<snip>
If you're the FBI, you ask a judge to approve a full "cell tower dump,"
in which wireless operators will turn over the records of every cell phone
that registered with a particular tower at a particular time.
(Phones "register" with the nearest cell towers so that the network knows how to route calls.)
And then you look for any numbers that stand out.
<snip>
The FBI actually received more than 150,000 registered cell phone numbers
from this particular set of tower dumps, despite picking the most rural locations possible.
What the case agents wanted to do was scan the logs from all four sites on the belief
that no single person was likely to be at all four banks during the robbery—except for the robber.

So the FBI dumped all the numbers into a Microsoft Access database and ran a query.
As expected, only a single number came back: Verizon Wireless phone number 928-205-xxxx
had registered with the tower closest to three of the banks on the day of each robbery.
(Verizon didn't have a cell tower covering the fourth bank.)
Further analysis found a second number, 928-358-xxxx,
that had been in contact with 928-205-xxx and that had registered with two of the towers in question.

The FBI then went back to the judge and obtained more particular
court orders covering these specific phone numbers.
The phone numbers came back with subscriber names attached: Joel Glore and Ronald Capito.
And the location data returned showed that these two phones had
been present at most of the 16 bank robberies under investigation.
Further, the data showed that both phones tended to travel from Show Low, Arizona,
to the location of each bank just before each robbery.
<snip>

BUT... About those 149,998 other numbers...

Bandits? Caught. Justice? Done.
But let's step back from the final result for a moment and ponder
the technique that provided the big lead —the cell tower dumps.
Should we have any concerns with the government getting that sort
of mass tracking information on so many Americans without a warrant?

Some judges say yes. Former Magistrate Judge Brian Owsley dealt routinely
with warrant requests and court orders until becoming a law school professor earlier this year;
he has just written an intriguing paper about the issues surrounding cell tower dumps.
In his view, these are clearly "searches" under the Fourth Amendment,
and they require a full warrant backed by evidence of "probable cause."

That's because the Supreme Court jurisprudence on surveillance has
relied for decades in part on the idea of someone's "reasonable expectation of privacy"
—and people certainly expect that their location won't be easily and routinely accessible
to law enforcement without a warrant, regardless of whether cell phone technology tracks them or not.