## Facts

- The government prosecuted Ledwin Castro and David Vasquez, alleged members of MS-13, for VICAR conspiracy and assaults with a dangerous weapon, and for discharging a firearm during crimes of violence.
- MS-13 was described at trial as a nationwide gang organized into local “cliques”; Castro was alleged to lead a Long Island clique.
- The government’s theory tied the charged assaults to MS-13 membership requirements and retaliatory violence against rival gangs.
- On June 18, 2003, Castro, Vasquez, and others met, planned attacks on rival gang members, obtained a handgun and ammunition, and used a stolen van to conduct two drive-by shootings on Long Island; injuries resulted.
- At trial, the government called NYPD Officer Hector Alicea as an expert on MS-13’s history, structure, and operations, including asserted numbers of MS-13 murders, weapons seizures, and other crimes.
- Alicea’s testimony substantially relied on custodial interrogations of MS-13 members, statements from other law-enforcement officers, recorded conversations, and “research,” and he could not clearly distinguish which assertions came from which sources.
- The jury convicted both defendants on all counts.

## Issues

1. Whether admitting the gang-expert testimony violated the Federal Rules of Evidence by functioning as a conduit for hearsay rather than supplying genuine expert analysis.
2. Whether the expert’s repetition of out-of-court statements from custodial interrogations and similar sources violated the Sixth Amendment Confrontation Clause.
3. Whether any evidentiary and constitutional error was harmless beyond a reasonable doubt.

## Decision

- The Second Circuit vacated the judgments of conviction and remanded for retrial.
- The court held that substantial portions of the expert testimony were improperly admitted under the Federal Rules of Evidence because they conveyed hearsay as substantive proof.
- The court held that admitting testimonial hearsay through the expert violated the Confrontation Clause because the declarants did not testify and were not subject to cross-examination.
- The court concluded the errors were not harmless given the testimony’s prominence and its role in establishing enterprise-related elements and motive for the VICAR charges.

## Legal Principles

- Under Federal Rule of Evidence 703, an expert may rely on inadmissible material if reasonably relied upon in the field, but may not serve as a “conduit” for hearsay presented to the jury as proof of disputed facts.
- Testimonial statements, including those taken during custodial interrogation for law-enforcement purposes, are inadmissible against a defendant unless the declarant is unavailable and the defendant had a prior opportunity to cross-examine.
- Labeling testimony as “expert” does not permit the government to introduce testimonial hearsay indirectly by presenting it as the basis for an expert opinion.
- Gang-expert testimony may provide limited contextual background, but it becomes inadmissible when it supplies case-critical factual assertions about prior crimes and organizational conduct used to prove elements such as enterprise and “in aid of” motive.
- When improperly admitted hearsay and confrontation violations are central to proving racketeering-related elements, appellate courts may not find the error harmless beyond a reasonable doubt.

## Conclusion

The convictions were vacated because the government’s gang expert relayed testimonial hearsay—particularly from custodial interrogations—as substantive evidence on key elements, violating evidentiary limits on expert testimony and the defendants’ Confrontation Clause rights, and the resulting error was not harmless.


United States v. Mejia, 545 F.3d 179 (2d Cir. 2008)