Can a defense interpreter be used to interpret for the Spanish-speaking prosecution witnesses at a criminal trial?

Defendant contends his constitutional rights were violated when the defense interpreter was borrowed to interpret for the Spanish-speaking prosecution witnesses. Those rights alleged to have been violated include the following: The state right to a court-appointed interpreter, the state and federal rights to confrontation and effective assistance of counsel, and the state and federal due process rights to a fair trial. Defendant's appeal may be resolved on the violation of the state constitutional right to an interpreter. Protection of this right encompasses a protection for all of the aforementioned rights. (People v. Aguilar (1984) 35 Cal.3d 785, 200 Cal.Rptr. 908, 677 P.2d 1198; People v. Carreon (1984) 151 Cal.App.3d 559, 198 Cal.Rptr. 843.)

Article I, section 14, of the California Constitution provides in pertinent part: "A person unable to understand English who is charged with a crime has a right to an interpreter throughout the proceedings." The initial question is whether defendant needed an interpreter. The right only arises when the accused cannot understand English. (People v. Carreon, supra, [161 Cal.App.3d 530] 151 Cal.App.3d at p. 567, 198 Cal.Rptr. 843.) Defendant's inability to understand English is undisputed on this appeal.