Electronic Frontier Foundation
Digital rights and surveillance accountability
Parallel construction is the government's secret method for laundering illegally-obtained evidence into criminal prosecutions. They've been doing it for decades. Most people never find out.
A law enforcement practice of building a separate evidentiary trail to hide the true—often unconstitutional—origins of an investigation. Evidence laundering.
The Fourth Amendment protects you from unreasonable searches and seizures. Evidence obtained illegally—without a warrant, through mass surveillance, or in violation of your rights—is supposed to be inadmissible in court.
Parallel construction is how law enforcement gets around that.
When agencies like the NSA, DEA, or FBI obtain information through methods they don't want disclosed—warrantless wiretaps, illegal surveillance, confidential sources they want to protect—they pass tips to local law enforcement. Those agencies then "reconstruct" the investigation using legal methods, creating a clean paper trail that hides the true origin.
You never know how they really found you. Your attorney can't challenge what they can't see. The jury never learns the truth.
NSA intercepts your communications through mass surveillance programs. FBI deploys StingRay devices without warrants. DEA's Special Operations Division receives tips from classified intelligence sources. The evidence would be thrown out if its source were known.
The prosecution presents only the reconstructed evidence. The original source—the warrantless surveillance, the illegal search, the classified program—is never mentioned. Defense attorneys can't challenge what they don't know exists.
Law enforcement has developed sophisticated methods to obscure the origins of investigations.
Intelligence from classified surveillance is repackaged as an anonymous call to a tip line. No caller ID. No way to trace. Impossible to challenge.
Officers know exactly who they're looking for and what they'll find. They tail the target until a minor traffic violation—broken taillight, failure to signal—gives them "probable cause."
A CI is manufactured or directed to provide information that mirrors what surveillance already revealed. The source becomes a person instead of an unconstitutional program.
Agents are trained to write reports that omit any reference to the true source. Prosecutors may not even know. The paper trail is clean by design.
Information passes through multiple agencies, each adding a layer of separation. By the time it reaches court, the chain is too convoluted to unravel.
Cell-site simulators track phones without warrants. When challenged, cases are dismissed rather than reveal the technology. If a case proceeds, the StingRay disappears from the record.
Parallel construction doesn't just violate the law—it corrupts the entire justice system.
Agents are instructed to omit the SOD's involvement from investigative reports, affidavits, discussions with prosecutors and courtroom testimony. Agents are told to 'ichever normal investigative techniques to recreate the information.'— Reuters Investigation, 2013
When the government hides how it found evidence:
• Defendants cannot challenge illegal searches
• Courts cannot enforce constitutional protections
• Prosecutors may not even know the truth
• Juries make decisions based on incomplete information
• Innocent people cannot prove misconduct
Despite efforts to keep it secret, journalists and watchdogs have documented parallel construction for years.
A bombshell investigation reveals the DEA's SOD has been funneling intelligence from NSA intercepts to local law enforcement, with explicit instructions to hide the source through parallel construction.
Read the investigation →Reporting reveals the DEA operated a bulk phone records program for over two decades, separate from NSA programs, collecting billions of call records from Americans—all kept secret from courts and defense attorneys.
"Dark Side" documents how parallel construction has become routine practice, undermining fair trial rights and making it nearly impossible for defendants to challenge unconstitutional surveillance.
Read the report →Legal scholars document how the Supreme Court's 2009 "good faith exception" ruling has enabled evidence laundering by protecting officers who rely on information from other agencies—even when the original collection was unconstitutional.
Police departments across the country sign NDAs with the FBI, agreeing to dismiss cases rather than reveal cell-site simulator use. Parallel construction remains the preferred method to hide the technology.
Atlanta Airport Threat Case (2025) — Red Flags for Parallel Construction
In October 2025, Billy Joe Cagle—a man with documented bipolar disorder and schizophrenia who had stopped taking his medications—was arrested at Hartsfield-Jackson Atlanta International Airport after his family reported he had made threats during a mental health crisis. An AR-15 was found in his truck. He was rapidly federalized and now faces charges including attempted violence at an international airport.
The official story: Family saw alarming social media posts, called police, and law enforcement intercepted him before tragedy struck. Case closed.
But several aspects of this case warrant scrutiny:
The FBI assumed jurisdiction almost immediately and began investigating how Cagle—a convicted felon—obtained the firearm. This level of instant federal interest is atypical for a local mental health crisis. How did they know to look into the gun sourcing so quickly? Did they already have intelligence on him?
Family tips are textbook cover for parallel construction. If federal agencies already had Cagle under surveillance—through phone monitoring, social media tracking, or database flags—a family report provides a clean, constitutional origin story for the investigation. The real source stays hidden.
Cagle fits a documented pattern: individuals with mental health challenges who are easier to monitor, predict, and—if needed—allow to reach a crisis point before intervention. If agencies knew he was spiraling and chose not to intervene until a dramatic arrest could be made, that raises serious questions.
Did any federal agency have records on Cagle before October 20, 2025? Were there Hemisphere/DAS phone queries? FISA or Section 702 collection? Any internal communications referencing parallel construction? If pre-existing surveillance exists, it's Brady material—and it strengthens the mental health defense by showing a vulnerable person was already in federal crosshairs.
Note: Billy Joe Cagle is presumed innocent. His defense attorneys are pursuing an insanity defense, arguing this was a medical crisis, not malicious criminal behavior. The questions raised here are about federal investigative practices, not guilt or innocence. If parallel construction was used in this case, Cagle's constitutional rights—and the integrity of the judicial process—have been compromised regardless of the outcome.
Parallel construction thrives in secrecy. Awareness, legal challenges, and policy reform can expose and end it.