Courts throw out cases in which the government violated the Fourth Amendment to gain evidence obtained illegally. Prosecutors, dreading such a rebuke, have sometimes resorted to “parallel construction” – using illicitly gained knowledge to turn up evidence from a source acceptable in court.
Suppose, for example, that an illegal wiretap by federal investigators reveals that a target will deliver drugs to a certain street corner. They could then alert local police to decide that specific corner is a good place for a spot-check with drug-sniffing dogs.
In this way, evidence obtained by illicit surveillance can be laundered. This seems to be especially prone to happen when law enforcement relies on “stingrays” – the common name for cell-site simulators, equipment that mimics a cellphone tower to ping the location of a cellphone.
The FBI, in 2014, after providing the Oklahoma City police with stingray technology, sent that department a memo telling the police that the stingray is for “lead purposes” only and “may not be used as primary evidence in any affidavits, hearings or trials.” Instead, the FBI required the police to use “additional and independent investigative means and methods, such as historical cellular analysis, that would be admissible at trial” to corroborate information obtained using the stingray. The Cato Institute’s Adam Bates analyzed such agreements and concluded that “law enforcement uses some surreptitious and, perhaps, constitutionally dubious tactics to generate a piece of evidence. In order to obscure the source of that evidence, police will use the new information as a lead to gather information from which they construct a case that appears to have been cracked using routine police work.”
Perhaps because of reporting like Cato’s analysis, formal FBI agreements to sell stingrays to local law enforcement – at least those released to the public – appear to be missing this language.
But what about informal agreements?
In two responses to PPSA’s Freedom of Information Act requests, the FBI has used similar language in 2015 and 2020 deals to allow police to use stingrays. To be fair, these may be one-off situations. Both cases seem to have been loaner deals, in which stingrays were deployed in “exigent” or emergency circumstances.
For example, one 2015 email chain shows that an agency agreed to the FBI’s request that “it is required to use additional and independent investigative means and methods, such as [redacted] that would be admissible at trial to corroborate information concerning the location of the target obtained through the use of this equipment.”
Comparing this redacted language to the unredacted provisions imposed on the Oklahoma City police, it appears that the FBI continues to push local law enforcement to hide their stingray use from the courts. On the other hand, this language is missing from other NDA forms PPSA has obtained. Has the FBI abandoned this practice? Or is it continuing “off the books” in some fashion to encourage local law enforcement to launder evidence?