The interview came after the human rights watchdog Privacy International managed to obtain a cache of documents which shed light on the UK spy agencies' controversial BPDs. This is the collection of personal data of people, most of whom present no particular interest to the intelligence services.
"It appears that the vast majority of data was supplied on a volunteer basis. I suspect that some of the information was being supplied by email providers or organizations that handled emails as well," Cohen said.
He expressed alarm about what he described as "the level of scrutiny" pertaining to the BPDs.
"I'm also concerned about the level of scrutiny carried out by unknown and unnamed officials, something that reminds [me] of dark days and even dark regimes," he said.
According to him, the documents are all about the way the information is being collected.
"What was actually disclosed is not the documents related to specific individuals but rather the policy that governs the collection of that data. By reading those documents we can understand what type of information was being handled and how it was delivered," he added.
Covering the decade from June 2005 to May 2015, they were released in response to a legal challenge filed by Privacy International last year. In particular, they provide information about what sort of personal information is included in BDPs, and how it is categorized and acquired.
According to the documents, the data is obtained through third-party voluntary suppliers. The key categories include info on an individual's biography, travel, finance and communications.
