In People v. Arreola (1994) 7 Cal.4th 1144, the defendant objected on several grounds to the use of a preliminary hearing transcript at a probation revocation hearing. The defendant asserted hearsay and lack of foundation in that there had been no showing of the declarant's unavailability or other good cause. The trial court admitted the transcript without finding good cause. (Id. at p. 1151.) The Court concluded that the arresting officer's testimony at a preliminary hearing on new charges forming the basis for revocation of probation was inadmissible at the probation revocation hearing absent a showing of good cause or witness unavailability. (Arreola, supra, at pp. 1159-1161.) Moreover, the good cause showing must be considered together with other relevant circumstances, including the purpose for which the evidence is offered, the significance of the evidence to the factual determination upon which the alleged probation violation is based, and whether other admissible evidence corroborated the evidence in question. (Id. at p. 1160.) In People v. Arreola (1994) the defendant claimed the trial court erroneously considered a preliminary hearing transcript in lieu of live testimony at his probation revocation hearing. Prior to the revocation hearing the defendant had been tried on the charges encompassed in the preliminary hearing. At this trial, Arreola was convicted of two misdemeanor charges (resisting and evading an officer). He was acquitted of driving with a blood-alcohol level of .08 percent or greater and the jury was unable to reach a verdict on the charge of driving under the influence of alcohol. The revocation hearing was not held before the same judge that presided over Arreola's trial. The judge revoked Arreola's probation finding that he had violated his terms of probation by driving under the influence and with a blood-alcohol level of .08 percent or greater, reckless driving while evading an officer, operating a vehicle without a valid driver's license, and resisting an officer. ( People v. Arreola, supra, 7 Cal.4th at pp. 1150-1151.) The Supreme Court found that the trial court erroneously considered the preliminary hearing transcript in making its decision, but the court found the error was harmless. Error was judged by the Chapman ( Chapman v. California (1967) 386 U.S. 18) standard. The Supreme Court took judicial notice of defendant's conviction for driving under the influence, which occurred after the probation revocation hearing. The court found that substantial evidence was presented, independent of the preliminary hearing transcript, to establish that defendant had violated his probation in several respects in the form of Department of Motor Vehicle printouts, and his convictions from his trial. The most serious of the alleged probation violations, driving under the influence, was, at the time of the probation revocation hearing, proven only by the erroneously admitted preliminary hearing transcript. But, defendant's subsequent conviction clearly established the particular violation of probation and thus rendered the error harmless. ( People v. Arreola, supra, 7 Cal.4th at pp. 1161-1162.) The Supreme Court concluded: "thus, affording defendant a new probation revocation hearing would be a futile act because, on remand, the trial court would have before it defendant's conviction of the offense whose circumstances formed the basis for that court's previous action revoking probation---a conviction that presently, in itself, would support a proper revocation of probation. " ( People v. Arreola, supra, 7 Cal.4th at p. 1162.) The California Supreme Court stated that, "as a means of avoiding needless duplication and promoting judicial economy, in some instances the preliminary hearing on the charges that give rise to the parole revocation proceeding may be coordinated with the final revocation hearing, in a single proceeding. " (Arreola, supra, 7 Cal.4th at p. 1159.) In such a joint proceeding, the court emphasized that the decision maker must satisfy the defendant's constitutional right of confrontation by "observing the demeanor of those witnesses who testify for purposes of the preliminary hearing" rather than "attempting to assess credibility from a cold record or deferring to the other judge's assessment of the witnesses' credibility." (Ibid.) The People argued that People v. Maki (1985) had clarified People v. Winson (1981), and permitted admission of the transcript when the former testimony bore sufficient indicia of reliability without any concomitant showing of good cause for not presenting the witness at the hearing; reliability was established if a defendant was notified before the preliminary hearing of the intent to use the transcript at a later probation revocation proceeding and had been given an adequate opportunity to cross-examine the witness at the earlier hearing. ( Arreola, supra, 7 Cal.4th at p. 1156.) The Supreme Court rejected these arguments and distinguished the admission of documentary evidence, found admissible in Maki or Brown, from hearsay used "as a substitute for the live testimony of an adverse witness at a revocation hearing." ( Arreola, supra, at pp. 1156-1157, ) Arreola explained at page 1157 that: "As we observed in Winson, the need for confrontation is particularly important where the evidence is testimonial, because of the opportunity for observation of the witness's demeanor. Generally, the witness's demeanor is not a significant factor in evaluating foundational testimony relating to the admission of evidence such as laboratory reports, invoices, or receipts, where often the purpose of this testimony simply is to authenticate the documentary material, and where the author, signator, or custodian of the document ordinarily would be unable to recall from actual memory information relating to the specific contents of the writing and would rely instead upon the record of his or her own action." Arreola confirms that at a probation hearing a defendant's right to confront and cross-examine testimonial evidence "may not be dispensed with lightly" ( Arreola, supra, 7 Cal.4th at p. 1158) based on some amorphous conclusion that the hearsay testimony is reliable. It instead appears that under Arreola testimonial hearsay may be admitted only for good cause. The prosecution can establish good cause either by making a traditional Evidence Code section 240 foundational showing of unavailability of the witness, or by satisfying a more relaxed unavailability standard, including situations in which securing the witness's testimony at the hearing involves "great difficulty or expense," or because there exists a risk of physical or emotional harm to the witness if required to appear. Moreover, the good cause determination must be assessed on a case by case basis, considering such factors as the purpose of the hearsay (is it "substantive evidence of an alleged probation violation, rather than, for example, simply a reference to the defendant's character"), and the significance of the particular evidence to the court's determination. ( Arreola, supra, at pp. 1159-1160.) The California Supreme Court reemphasized the importance of confrontation in revocation hearings and distinguished "the type of traditional 'documentary' evidence involved in Maki that does not have, as its source, live testimony." (Id. at p. 1157.) The court held inadmissible the transcript of a preliminary hearing showing the defendant drove a vehicle while under the influence of alcohol. The court stated, "As we observed in People v. Winson (1981), the need for confrontation is particularly important where the evidence is testimonial, because of the opportunity for observation of the witness's demeanor. Generally, the witness's demeanor is not a significant factor in evaluating foundational testimony relating to the admission of evidence such as laboratory reports, invoices, or receipts, where often the purpose of this testimony simply is to authenticate the documentary material, and where the author, signator, or custodian of the document ordinarily would be unable to recall from actual memory information relating to the specific contents of the writing and would rely instead upon the record of his or her own action." (Ibid.) The court emphasized that a showing of good cause for the admission of hearsay at a probation revocation hearing is "compelled by the due process requirements imposed by the United States Supreme Court." (Id. at pp. 1157-1158.) It quoted and emphasized the following statement by the United States Supreme Court regarding former testimony: " 'If the declarant is available and the same information can be presented to the trier of fact in the form of live testimony, with full cross-examination and the opportunity to view the demeanor of the declarant, there is little justification for relying on the weaker version.' " (Id. at pp. 1158-1159.) Arreola set forth the following principles regarding the showing of good cause required to deny the defendant confrontation by admitting former testimony: "The broad standard of ... 'good cause' is met (1) when the declarant is 'unavailable' under the traditional hearsay standard (see Evid. Code, 240), (2) when the declarant, although not legally unavailable, can be brought to the hearing only through great difficulty or expense, or (3) when the declarant's presence would pose a risk of harm (including, in appropriate circumstances, mental or emotional harm) to the declarant." (Arreola, supra, 7 Cal.4th at pp. 1159-1160.) "In determining the admissibility of the evidence on a case-by-case basis, the showing of good cause that has been made must be considered together with other circumstances relevant to the issue, including the purpose for which the evidence is offered (e.g., as substantive evidence of an alleged probation violation, rather than, for example, simply a reference to the defendant's character); the significance of the particular evidence to a factual determination relevant to a finding of violation of probation; and whether other admissible evidence, including, for example, any admissions made by the probationer, corroborates the former testimony, or whether, instead, the former testimony constitutes the sole evidence establishing a violation of probation." (Id. at p. 1160.)