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California Supreme Court Announces Predicate Offenses for Gang Enhancement or Gang Participation Not Provable Using Expert Witness Testimony Without Personal Knowledge of Facts

by Matt Clarke

The Supreme Court of California held that, for charges of gang participation and gang enhancements under California Penal Code, § subdivisions (a)and (b), respectively, which require the State to prove that gang members had previously committed two or more enumerated offenses (predicate offenses), the State may not prove the predicate offenses using the testimony of an expert witness who has no personal knowledge of the facts of those offenses. This affirmed the Court of Appeal decision reversing gang participation, gang enhancements, and attached firearms allegations.

A police officer on patrol in Arvin, California, witnessed a drive-by shooting at a carwash in which a person was wounded. This resulted in an hour-long vehicular chase. The officer could identify the shooter and driver, and a revolver cylinder thrown from the vehicle during the chase was recovered.

Jose Luis Valencia and Edgar Isidro Garcia were arrested and charged with two counts of attempted murder, assault with a firearm, and active street gang participation. Garcia was also charged with shooting from a vehicle. Valencia was also charged with evading an officer and knowingly allowing a passenger to shoot from a vehicle. Gang and firearms enhancements were attached to various charges.

At trial, Arvin Police Officer Ryan Calderon, a nine-year veteran who specializes in gang crimes, testified as a gang expert. He described the Arvina 13 gang’s criminal activities, colors, symbols, tattoos, and territory, which included the carwash. Based on their tattoos and previous police contacts, he opined that Valencia and Garcia were members of the Arvina 13 street gang.

Responding to a hypothetical question, Calderon testified that the carwash shooting benefited Arvina 13 by creating community fear and gang notoriety. He also testified about the facts of three other Arvina 13 members who previously committed felonies, two assaults and an attempted robbery. He admitted that his only knowledge of those crimes came from conversations with other police officers and a review of police reports. Certified copies of court documents related to their convictions were admitted into evidence.

Valencia and Garcia were convicted on all charges and given multiple consecutive sentences of up to life. They appealed.

The Court of Appeal reversed the active gang participation and gang enhancement allegations and Valencia’s attached firearms enhancement, affirming the remaining parts of the judgments. The State successfully petitioned the California Supreme Court for review, and the Court appointed

attorneys Elizabeth J. Smutz and Hilda Sceib to represent Garcia and Valencia, respectively, then consolidated the cases.

The Supreme Court recounted the history of the California Street Terrorism Enforcement and Prevention (“STEP”) Act of 1988, Pen. Code § 186.20 et seq., that created the offense of gang participation and the sentencing enhancements for a felony committed “for the benefit of, at the direction of, or in association with any criminal street gang” that “requires proof that gang members committed at least two predicate offenses within the statutory timeframe.” This requires evidence of: when the crime was committed; who committed it; the perpetrator being gang member; and the type of crime committed. § 186.22.

An expert is permitted to testify concerning the expert’s general knowledge even if it is technically hearsay in that it was derived from lectures, conversations, or the study of learned treatises. People v. Sanchez, 374 P.3d 320 (Cal. 2016). However, an expert is generally not permitted to supply case-specific facts about which the expert has no personal knowledge. Id. But the Court explained that “an expert’s opinion based on case-specific facts outside the expert’s personal knowledge can still be accomplished through the use of hypothetical questions.” See id.

The Court observed that the determinative issue in the present case is whether the gang expert’s testimony constitutes background information or case-specific facts. The leading cases on this issue—Sanchez and People v. Veamatahau, 459 P.3d 10 (Cal. 2020)—make it clear that experts are permitted greater latitude than lay witnesses to testify about matters beyond their personal knowledge because they are allowed to provide their opinion on subjects beyond the common experience of the general public and thus their opinion would assist the trier of fact. As long as the expert is testifying about a matter that is generally accepted in the expert’s field of expertise (i.e., background facts) or supported by the expert’s own personal experience, the expert’s testimony will generally be admitted. See Sanchez. In contrast, if the expert’s testimony goes beyond what’s generally accepted in his or her field or not based on personal experience, then the rationale for granting the expert greater latitude to testify about hearsay evidence ceases. See id.

Turning to the present case, the Court rejected the State’s assertion that “facts used to prove predicate offenses are merely background information properly supplied by expert testimony.”

General testimony about a gang’s behavior, history, and territory are generally admissible via expert witness testimony, even if hearsay, because these are matters experts can all agree upon and thus are consider reliable and accurate by gang experts. See id. However, the Court explained that information about the commission of a specific offense on a specific occasion constitutes case-specific facts and “are not the kind of general information on which experts can be said to agree.” The Court stated: “Without independent admissible evidence of the particulars of the predicate offenses, the expert’s hearsay testimony cannot be used to supply them.” Thus, the Court ruled that Calderon’s testimony regarding the facts of the three predicate offenses of which he lack personal knowledge was inadmissible hearsay.

As to whether the error was prejudicial, the Court noted that the applicable standard is the federal constitutional standard of Chapman v. California, 386 U.S. 18 (1967), which requires any error to be harmless beyond a reasonable doubt. The Court ruled that based “on the extent of the evidence and the elements it was offered to prove, we cannot conclude that the error was harmless under the Chapman standard.”  

Accordingly, the Court affirmed the judgment of the Court of Appeal. See: People v. Valencia, 2021 Cal. LEXIS 4445 (2021).

Editor’s note: For anyone interested in the issue of expert witness testimony on general background information versus case-specific facts, the Court explains the difference between the two types of testimony in detail. 

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Related legal cases

People v. Valencia

People v. Veamatahau

People v. Sanchez



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