When the 74-count indictment of Daniel David Rigmaiden on tax, mail and wire fraud charges was revealed in 2010, a local Arizona newspaper said Rigmaiden had fallen prey to one of "the oldest steps in the law-enforcement playbook: a confidential informant."
A snitch may have helped bring Rigmaiden down. But there was another informant in the case, an electronic one. And ever since Rigmaiden's indictment was unveiled, the U.S. Department of Justice has fought doggedly to keep the public in the dark about how exactly it was used.
In a U.S. District Court of Arizona hearing on Thursday, the government is finally being forced to defend its use of a secretive cell phone tracking device called a stingray. Days before the hearing, the government admitted a key error in its use of court orders for stingrays.
If civil liberties advocates had their pick of who would become a case study in the use of 21st century phone tracking technology, they would probably not choose Rigmaiden. The federal government alleges that under the alias "the hacker," he organized a complex, multi-state operation to defraud the Internal Revenue Service. His co-conspirators never knew him by name: He allegedly used a wireless aircard and anonymous Internet addresses to connect with them.
It was that card that led the feds to his front door. Federal law enforcement agents trawled the San Francisco Bay Area with a stingray, which simulates a legitimate cell tower and forces phones to reveal their location and unique ID numbers.
"When the government uses this stuff, they drive through a neighborhood. They send signals through the walls of every home in the neighborhood," said Christopher Soghoian, principal technologist at the American Civil Liberties Union's Speech Privacy and Technology Project.
Soghoian compared the technology to the robots in "Minority Report," the "little insect-type robots that crawl under people's doors and then force open people's eyelids and scan their eyes." But at least in that movie, he added, "they're only looking for a particular, known target."
Stingrays, Soghoian argued, violate Americans' Fourth Amendment right "to be secure in their … houses" and its prohibition against general warrants not tailored to one person. The federal government has said it takes pains to delete information unrelated to the targets of its investigations.
The government's use of stingrays even in relatively low-level tax fraud cases might never have become known if Rigmaiden weren't a dogged jailhouse lawyer, someone who has churned through several court-appointed attorneys and now represents himself. Rigmaiden has been in jail since 2008, but it took until 2011 to force the government to admit that it had used a stingray against him.
The federal judge in Rigmaiden's case is considering whether to throw out the evidence collected by the phone tracking device -- and all the fruits of the searches thereafter. That could conceivably mean Rigmaiden walks.
One central issue is whether the court order used to hunt down Rigmaiden with a stingray counts as a proper warrant. The ACLU of Northern California, which has filed a friend-of-the-court brief in the case, argues that since the government did not specifically tell the judge that it was going to use a stingray, the subsequent search was invalid.
In a document released March 22, the government revealed what the ACLU had long suspected: that in similar cases, U.S. attorneys have often failed to disclose to front-line magistrate judges that they are using stingrays. Instead, they've made their applications read like standard requests for basic cell phone surveillance methods, called pen registers, that record only the numbers of incoming and outgoing calls.
"It has recently come to my attention that many agents" were using stingrays, San Francisco federal prosecutor Miranda Kane wrote in the May 2011 email, "although the pen register application does not make that explicit."
"While we continue work on a long term fix for this problem it is important that we are consistent and forthright in our pen register requests," she added.
As Kane's email suggests, the federal government has been under increasing pressure from judges to obtain a warrant before it uses stingrays. In court filings related to the Rigmaiden stingray case, the government has essentially claimed that the court orders it obtained were nothing out of the ordinary.
U.S. District Judge David G. Campbell has told prosecutors that they should be prepared to support that assertion.
"There's a lot riding on this," said Linda Lye, the ACLU attorney making her group's argument as a third party in Thursday's hearing. The government has a legal "duty of candor" to be honest with judges when it does things like apply for search warrants or pen registers. The question in this case, Lye said, is "what does that 'duty of candor' mean when it comes to new technology?"