Rochelle Lonel Gardeley and Tommie James Thompson (defendants) were charged with violation of California’s Street Terrorism Enforcement and Prevention Act (STEP) in connection with an alleged assault of Edward Bruno (they were also charged with attempted murder, assault with a deadly weapon, and robbery). A third assailant, Tyrone Watkins, pled guilty to violation of the STEP Act before Gardeley and Thompson’s trial. Gardeley, Thompson, and Watkins were members of a gang called the Family Crips. The STEP Act imposes an additional penalty on defendants when a crime is committed in association with a “criminal street gang,” where a criminal street gang is an association of individuals that (1) has a primary activity of committing crimes and (2) engages in a “pattern of criminal gang activity.” Criminal gang activity is defined as committing two or more crimes. At trial, the prosecution brought Detective Patrick Boyd of the San Jose Police Department as an expert on criminal gang activity. Boyd was given a hypothetical situation with the facts surrounding Bruno’s assault and in response he testified that this was a classic example of gang-related activity. Boyd also testified that the Family Crips’s primary purpose was to sell narcotics and that its members had committed multiple crimes. Much of Boyd’s testimony was based on interviews Boyd had taken of Gardeley, Thompson, and Watkins after their arrests, conversations with other Family Crip members, and conversations with various law enforcement officers regarding three different criminal incidents involving members of the Family Crips. The testimony was objected to by Gardeley and Thompson on hearsay grounds. The trial court allowed the testimony and convicted Gardeley and Thompson of violating the STEP Act (along with the substantive crimes). The court of appeal reversed the conviction on the violation of the STEP Act, reasoning that Boyd’s testimony that the three criminal incidents were gang-related was inadmissible because the facts of the incidents were not admitted as evidence and he did not have firsthand knowledge of the facts. The prosecution appealed.