REUTERS/Rick Wilking
While Hemisphere was first revealed in 2013 by The New York Times, the Daily Beast reported on new documents it obtained that showed the program is much larger than initially thought, and that law enforcement does not need a search warrant before using the database, but instead needs only an administrative subpoena.
While probable cause is needed before issuing a search warrant, an administrative subpoena only requires a government agent to declare the information they may obtain could be "relevant" to an investigation.
AT&T received more than 103,000 subpoenas from January to June of this year, but only about 20,000 search warrants showing probable cause, according to the company's transparency report. The report does not offer specifics.
The Times reported in 2013 that Hemisphere was a "partnership" between AT&T and federal and local law enforcement engaged in drug investigations, where the government was paying the company to place its employees with counter-drug units throughout the country.
The program, started in 2007, is highly secretive. Training slides obtained by the Times detail steps to protect the program from public view and "keep the program under the radar." Law enforcement agencies who use the program, the slides show, are also instructed to never refer to Hemisphere by name in official documents.
How it actually works
To query Hemisphere, law enforcement agencies - which pay anywhere from $77,000 to $1 million a year for access - need to make a request for data on a given phone number, according to the Daily Beast's report. The request is made to an AT&T employee who will mine the database and give law enforcement the information within, which includes phone metadata, such as call times, who was called, and the location of the subscriber's phone, the report says.
This data, however, is not to be used as evidence in court, documents obtained by the Daily Beast show.
Since evidence obtained through Hemisphere cannot be used, it's clear that law enforcement must instead use it to find other evidence it can legitimately use in a courtroom without indicating the initial source - a controversial practice known as "parallel construction."
The DEA routinely uses this method in investigations they are initially tipped to by classified intelligence given by the CIA or NSA.
"Our investigations must be transparent. We must be able to take our information to court and prove to a jury that our bad guy did the bad things we say he did," a training slide from the DEA, made public in 2014, reads. "However, we are also bound to protect certain pieces of information so as to protect the sources and methods."
While the Times focused on the anti-drug aspect of the program, it turns out that Hemisphere has been used in other ways, such as in homicide investigations or Medicaid fraud.
"Like other communications companies, if a government agency seeks customer call records through a subpoena, court order or other mandatory legal process, we are required by law to provide this non-content information, such as the phone numbers and the date and time of calls," Fletcher Cook, a spokesperson for AT&T, told Business Insider.