A day after we learned of a draining turf battle between the NSA and other law enforcement agencies over bulk surveillance data, it now appears that those same agencies are working together to cover up when those data get shared.

The Drug Enforcement Administration has been the recipient of multiple tips from the NSA. DEA officials in a highly secret office called the Special Operations Division are assigned to handle these incoming tips, according to Reuters. Tips from the NSA are added to a DEA database that includes "intelligence intercepts, wiretaps, informants and a massive database of telephone records." This is problematic because it appears to break down the barrier between foreign counterterrorism investigations and ordinary domestic criminal investigations.

Because the SOD's work is classified, DEA cases that began as NSA leads can't be seen to have originated from a NSA source.

So what does the DEA do? It makes up the story of how the agency really came to the case in a process known as "parallel construction." Reuters explains:

Some defense lawyers and former prosecutors said that using "parallel construction" may be legal to establish probable cause for an arrest. But they said employing the practice as a means of disguising how an investigation began may violate pretrial discovery rules by burying evidence that could prove useful to criminal defendants.

The report makes no explicit connection between the DEA and the earlier NSA bulk phone surveillance uncovered by former Booz Allen Hamilton contractor Edward Snowden. In other words, we don't know for sure if the DEA's Special Operations Division is getting its tips from the same database that's been the subject of multiple congressional hearings in recent months. We just know that a special outfit within DEA sometimes gets tips from the NSA.

There's another reason the DEA would rather not admit the involvement of NSA data in its investigations: It might lead to a constitutional challenge to the very law that gave rise to the evidence.

Earlier this year, a federal court said that if law enforcement agencies wanted to use NSA information in court, they had to say so beforehand and give the defendant a chance to contest the legality of the surveillance. Lawyers for Adel Daoud, who was arrested in a federal sting operation and charged with trying to detonate a bomb, suspect that Daoud was identified using NSA information but was never told.

Surveys show most people support the NSA's bulk surveillance program strongly when the words "terrorism" or "courts" are included in the question. When pollsters draw no connection with terrorism, support tends to wane. What will happen when the question makes clear that the intelligence not only isn't being used for terrorism investigations against foreign agents, but is actively being applied to criminal investigations against Americans?

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Correction: This piece originally described the information provided to the DEA as "Section 702 phone records," but the Reuters report doesn't specifically identify the type of information shared. The article has been edited accordingly.