The case arose from a November 2014 arrest in Canóvanas, Puerto Rico, where four officers from a drug unit assaulted 17-year-old Calep Carvajal. Officer Carlos Nieves shot Carvajal in the back as he fled on a bicycle, and Cartagena tackled him, handcuffed him, and allegedly pistol-whipped him in the head while he lay unarmed on the ground.
The assault continued in the squad car, where prosecutors said Cartagena punched Carvajal twice in the face as the teenager tried to avoid blows from other officers. Three officers later pleaded guilty, but Cartagena went to trial and was convicted on all four counts, including two civil rights violations, filing a false police report, and obstructing justice.
The First Circuit found that the government violated Cartagena's Sixth Amendment rights by allowing a medical expert, Dr. Yocasta Brugal, to testify about statements Carvajal made during a medical examination. Circuit Judge Hamilton, writing for a unanimous panel, noted that Dr. Brugal relayed to the jury that Carvajal said he received a head trauma produced by the butt of a revolver.
The court emphasized that Carvajal never testified at trial because prosecutors were unable to locate him, depriving Cartagena of any opportunity for cross-examination. Hamilton rejected the government's argument that the statement was offered merely for context, writing that the prosecution's reliance on Federal Rule of Evidence 703 "defeats itself."
Hamilton explained that Carvajal's statement could have helped the jury evaluate Dr. Brugal's opinions only if it were true. If Carvajal did not remember how he received the wound or if he lied, the statement would have hindered the jury's ability to assess the expert's opinions by giving jurors false confidence in her conclusions.
The panel found the Confrontation Clause error was not harmless because Dr. Brugal was "easily the most trustworthy witness who testified against Cartagena as to Count 1." The court noted her extensive experience as a medical school dean and forensic expert, while other government witnesses had serious credibility problems.
Officer Lopez was facing ten years to life on unrelated drug theft charges before agreeing to cooperate, and Agent Brian Doyle's testimony relied on his six-year-old memory and FBI reports that were summaries of understanding rather than memoranda of what witnesses actually said.
The government's closing argument demonstrated the centrality of Dr. Brugal's testimony, with prosecutors telling the jury that Dr. Brugal was the one witness who explained how Carvajal sustained his injuries, specifically noting his statement that he was hit in the head with a gun.
Hamilton concluded that the Confrontation Clause error was not harmless beyond a reasonable doubt, requiring vacatur of the pistol-whipping conviction. The court affirmed Cartagena's convictions for punching Carvajal in the squad car, filing the false report, and obstructing justice by lying to prosecutors.