Cal. Stds. Jud. Admin., std. 2.10

(a) When an interpreter is needed

An interpreter is needed if, after an examination of a party or witness, the court concludes that:

(1) The party cannot understand and speak English well enough to participate fully in the proceedings and to assist counsel; or

(2) The witness cannot speak English so as to be understood directly by counsel, court, and jury.

(b) When an examination is required

The court should examine a party or witness on the record to determine whether an interpreter is needed if:

(1) A party or counsel requests such an examination; or

(2) It appears to the court that the party or witness may not understand and speak English well enough to participate fully in the proceedings.

(c) Examination of party or witness

To determine if an interpreter is needed, the court should normally include questions on the following:

(1) Identification (for example: name, address, birthdate, age, place of birth);

(2) Active vocabulary in vernacular English (for example: "How did you come to the court today?" "What kind of work do you do?" "Where did you go to school?" "What was the highest grade you completed?" "Describe what you see in the courtroom." "What have you eaten today?"). Questions should be phrased to avoid "yes" or "no" replies;

(3) The court proceedings (for example: the nature of the charge or the type of case before the court, the purpose of the proceedings and function of the court, the rights of a party or criminal defendant, and the responsibilities of a witness).

(d) Record of examination

After the examination, the court should state its conclusion on the record. The file in the case should be clearly marked and data entered electronically when appropriate by court personnel to ensure that an interpreter will be present when needed in any subsequent proceeding.

(e) Good cause for preappearance interview

For good cause, the court should authorize a preappearance interview between the interpreter and the party or witness. Good cause exists if the interpreter needs clarification on any interpreting issues, including: colloquialisms, culturalisms, dialects, idioms, linguistic capabilities and traits, regionalisms, register, slang, speech patterns, or technical terms.