That section provides in part that "when a detached act, declaration, conversation, or writing is given in evidence, any other act, declaration, conversation, or writing, which is necessary to make it understood, may also be given in evidence." In People v. Kent, 135 Cal.App.2d 422, 428 [ 287 P.2d 402], the court stated: "The rule that where part of a conversation has been shown in testimony the remainder of that conversation may be brought out by the opposing party, is necessarily subject to the qualification that the court may exclude those portions of the conversation not relevant to the items thereof which have been introduced." (See also People v. McCoy, 25 Cal.2d 177, 187 [ 153 P.2d 315]; People v. Kiser, 24 Cal.App. 540, 546 [ 141 P. 1078].)
[15] The general rule that where part of a conversation has been shown in testimony, the remainder of that conversation may be brought out by the opposing party (Code Civ. Proc., § 1854; Rosenberg v. Wittenborn (1960) 178 Cal.App.2d 846, 852-853 [ 3 Cal.Rptr. 459] and authorities there collected; Witkin, Cal. Evidence (1958) p. 677; McCormick on Evidence, pp. 131-132; 20 Am.Jur., Evidence, § 551, pp. 463-464) is necessarily subject to the qualification that the court may exclude those portions of the conversation not relevant to the items thereof which have been introduced. ( Witt v. Jackson (1961) 57 Cal.2d 57, 66-67 [ 17 Cal.Rptr. 369, 366 P.2d 641]; People v. McCoy (1944) 25 Cal.2d 177, 186-187 [ 153 P.2d 315]; People v. Valles (1961) 197 Cal.App.2d 362, 370-371 [ 17 Cal.Rptr. 204]; People v. Kent (1955) 135 Cal.App.2d 422, 428 [ 287 P.2d 402].) In Valles, supra, the court, quoting from People v. Richards (1946) 74 Cal.App.2d 279, 288 [ 168 P.2d 435], stated that what is meant by Code of Civil Procedure section 1854 is that "where part of a conversation . . . material and relevant to the issues of a case is given in evidence, the other parts of such conversation . . . having relevant reference to the part given may also be introduced."
[2] Portions of a statement not relevant to the part introduced properly may be excluded. ( Crosby v. Martinez, 159 Cal.App.2d 534, 539-540 [ 324 P.2d 26]; Estate of Nunes, 140 Cal.App.2d 744, 746 [ 296 P.2d 29]; People v. Kent, 135 Cal.App.2d 422, 428 [ 287 P.2d 402].) [1b] The refusal of the trial court to permit the introduction of the whole of Mr. Mooren's statement was not error.
This rule of completeness is designed to prevent the jury from obtaining a misleading impression, and it is subject to the requirement that the omitted portions be relevant to the admitted portions. (People v. Samuels (2005) 36 Cal.4th 96, 130; People v. Kent (1955) 135 Cal.App.2d 422, 428.) Although the meaning of NA related to Avila's statement that she was driving from an NA meeting, the statement was merely background information with no relevance to the purpose of her testimony, which was to describe the events surrounding the shooting.
The test of admissibility has been said to be whether the additional matter is relevant to the portion previously introduced. Rosenberg v. Wittenborn, 178 Cal.App.2d 846, 3 Cal.Rptr. 459; People v. Kent, 135 Cal.App.2d 422, 287 P.2d 402. In substance, the admitted portion constitutes an admission by Witt that he didn't turn on the red roof lights until he had pulled up alongside the Dodge.
Section 1854, Code of Civil Procedure, provides: "When part of an act, declaration, conversation, or writing is given in evidence by one party, the whole on the same subject may be inquired into by the other; when a letter is read, the answer may be given; and when a detached act, declaration, conversation, or writing is given in evidence, any other act, declaration, conversation, or writing, which is necessary to make it understood, may also be given in evidence." This seems to be but a codification of a generally prevailing rule and to be subject only to the qualification that the additional matter be relevant to the portion previously introduced ( People v. Kent, 135 Cal.App.2d 422, 428 [287 P.2d 408]) or, as phrased in the statute, "necessary to make it understood." This does not presuppose or have any necessary relationship to ambiguity in the primary admission; the rule is broader than that, as broad as principles of fair play may demand.