OPINION

BURKE, J.

This case, and two other cases before this court, raise important questions regarding the permissible extent of pretrial discovery by the prosecution in a criminal case. Petitioner herein, a defendant in a pending murder case, seeks to enjoin enforcement of a discovery order compelling her attorney to disclose to the prosecution the names, addresses and expected testimony of the witnesses petitioner intends to call at trial.

Petitioner asserts that to enforce the foregoing order would violate the privilege against self-incrimination, the attorney-client privilege, the right to effective counsel, and the right to a fair trial. (1a) We have concluded that the discovery order was in excess of the court's jurisdiction, and therefore void, in that it does not clearly appear from the face of the order or from the record below that the information demanded from petitioner cannot possibly have a tendency to incriminate her.

The People contend that the discovery order was proper under our decisions in Jones v. Superior Court, 58 Cal.2d 56 [ 22 Cal.Rptr. 879, 372 P.2d 919, 96 A.L.R.2d 1213], and People v. Pike, 71 Cal.2d 595 [ 78 Cal.Rptr. 672, 455 P.2d 776]. In Jones, we upheld a discovery order to the extent that it required a defendant in a rape case to disclose to the prosecution the names and addresses of the witnesses defendant intended to call, and the medical reports and X-rays he intended to introduce, in support of his defense of impotence. We relied upon the fact that several states had enacted statutory provisions requiring disclosure of alibi witnesses, and we noted that these provisions had been uniformly upheld against the claim that they violated the privilege against self-incrimination. ( 58 Cal. 2d at pp. 61-62.) We concluded in Jones that disclosure of the foregoing information would not violate the privilege against self-incrimination or the attorney-client privilege, since the identity of defendant's witnesses and the existence of medical reports and X-rays necessarily would be revealed by defendant at trial, and since disclosure of that information could not assist the prosecution in preparing its case in chief against defendant, even though it could assist in rebutting his defense of impotence. (58 Cal.2d at pp. 61-62.)

In People v. Pike, supra, we relied upon Jones and held that it was not prejudicial error to require defense counsel to disclose to the prosecution the names, addresses and expected testimony of defense witnesses prior to the retrial of the penalty phase of a murder trial.

Neither Jones nor Pike is directly controlling on the question presented by the discovery order in the instant case. Jones did not state that a defendant could be required to disclose the names and addresses of all defense witnesses, without regard to the subject matter and possible incriminatory nature of their testimony; nor did Jones involve an order seeking disclosure of the "expected testimony" of defense witnesses. Pike, in finding no prejudicial error in the discovery order involved therein, did not purport to extend permissible discovery beyond the limits previously established in Jones, upon which Pike exclusively relied. (See also People v. Lopez, 60 Cal.2d 223, 244 [ 32 Cal.Rptr. 424, 384 P.2d 16].)

Our decision in Jones was based primarily upon our conviction that since discovery is a valuable tool for ascertaining the truth, it should be conducted along a "two-way street" in criminal as well as civil proceedings, to the extent permitted by constitutional principles. We readily acknowledge that pretrial disclosure would greatly facilitate the administration of criminal justice by minimizing the element of surprise, avoiding unnecessary delays and continuances, reducing inconvenience to the court, counsel, jurors and witnesses, and permitting more effective pretrial preparation. However, certain significant developments in the law since Jones was decided in 1962 caution us not to extend its holding beyond its facts without careful consideration of the possible effects which such an extension could have upon the accused's rights and privileges, and especially his fundamental right not to be compelled to be a witness against himself. (2) First of all, the United States Supreme Court, in a series of landmark decisions, has placed increasing emphasis upon the role played by the Fifth Amendment privilege against self-incrimination in protecting the rights of the accused. The privilege is now an element of due process protected against state action by the Fourteenth Amendment, and federal standards govern in state proceedings ( Malloy v. Hogan, 378 U.S. 1 [12 L.Ed.2d 653, 84 S.Ct. 1489]); the prosecution and trial court are now forbidden to comment or instruct upon the accused's silence, or his reliance upon the privilege ( Griffin v. California, 380 U.S. 609 [14 L.Ed.2d 106, 85 S.Ct. 1229]); and the application of the privilege to the accusatory stage has been considerably broadened ( Miranda v. Arizona, 384 U.S. 436 [16 L.Ed.2d 694, 86 S.Ct. 1602, 10 A.L.R.3d 974]).

In addition, we note that in 1966 rule 16, subdivision (c) of the Federal Rules of Criminal Procedure was promulgated by the United States Supreme Court under its rulemaking power, to provide for certain limited discovery by the prosecution. As we are now governed by federal standards in determining the scope of the privilege against self-incrimination, we can profit from a review of the federal approach to criminal discovery. Rule 16, subdivision (c), which is conditioned upon defendant's request for discovery from the government, permits the court in its discretion to require defendant to disclose to the government "scientific or medical reports, books, papers, documents, tangible objects, or copies or portions thereof, which the defendant intends to produce at the trial and which are within his possession, custody or control, upon a showing of materiality to the preparation of the government's case and that the request is reasonable."

Thus, federal rule 16, subdivision (c), is limited to the "reasonable" disclosure of physical evidence; there is no provision authorizing disclosure of names, addresses or expected testimony of defense witnesses. However, even the limited discovery contemplated under rule 16, subdivision (c), has been attacked as violative of the accused's privilege against self-incrimination.

Furthermore, recent cases in the area of criminal discovery demonstrate increased concern that an accused's Fifth Amendment rights be not overlooked in the course of pursuing the truth along Jones' "two-way street." As stated above, Jones relied heavily upon the assumed constitutionality of state "alibi" statutes. However, the federal district court in Cantillon v. Superior Court (C.D. Cal. 1969) 305 F. Supp. 304 (appeal filed with 9th Cir.) granted habeas corpus to annul a discovery order which required petitioner-attorney to disclose to the prosecution the names of the alibi witnesses whom defendant-client intended to call at trial. The court reasoned that to compel such disclosure would violate defendant's privilege against self-incrimination, the attorney-client privilege, and the right to effective counsel.

Finally, the United States Supreme Court recently granted certiorari in Williams v. Florida (Fla.App.) 224 So.2d 406, which had upheld Florida's alibi statute against the claim that it violated the accused's Fifth Amendment rights. (See also United States v. Kordel, (1970) 397 U.S. 1 [25 L.Ed.2d 1, 90 S.Ct. 763].)

We had occasion, in People v. Schader, 71 Cal.2d 761, 770 [ 80 Cal.Rptr. 1, 457 P.2d 841], to analyze the policy which underlies the privilege against self-incrimination and recognized, ". . . with the United States Supreme Court, `that the American system of criminal prosecution is accusatorial, not inquisitorial, and that the Fifth Amendment privilege is its essential mainstay. . . . Governments, state and federal, are thus constitutionally compelled to establish guilt by evidence independently and freely secured, and may not by coercion prove a charge against the accused out of his own mouth.' ( Malloy v. Hogan (1964) 378 U.S. 1, 7-8. . . .) The People must `shoulder the entire load' of their burden of proof in their case in chief, without assistance either from the defendant's silence or from his compelled testimony. [Citations]." (See also Murphy v. Waterfront Com. of N.Y. Harbor, 378 U.S. 52, 55 [12 L.Ed.2d 678, 681-682, 84 S.Ct. 1594].)

However, we also pointed out in Schader that once a defendant voluntarily elects to testify in his own defense, nothing prevents the prosecutor from inquiring fully into the facts and circumstances surrounding his assertions or from introducing evidence through cross-examination which explains or refutes his statements. (71 Cal.2d at p. 770.)

Similarly, in Jones we explained that "Unlike an ordinary witness, a defendant need make no showing that the answer or document sought may be incriminating [citation], for the very fact that the prosecution seeks it, establishes that in the prosecution's view it may be incriminating [citation]." ( 58 Cal. 2d at p. 60.) Nevertheless, in Jones we permitted the prosecution to discover certain limited information pertaining to defendant's defense of impotence based upon our conviction that such information could not possibly incriminate him.

Thus, if we analyze Jones in the light of the policy considerations discussed in Schader, it is apparent that the principal element in determining whether a particular demand for discovery should be allowed is not simply whether the information sought pertains to an "affirmative defense," or whether defendant intends to introduce or rely upon the evidence at trial, but whether disclosure thereof conceivably might lighten the prosecution's burden of proving its case in chief. Although the prosecution should not be completely barred from pretrial discovery, defendant must be given the same right as an ordinary witness to show that disclosure of particular information could incriminate him.

(3) An ordinary witness need not actually prove the existence of an incriminatory hazard as that would surrender the very protection which the privilege against self-incrimination was designed to guarantee. Instead, the privilege forbids compelled disclosures which could serve as a "link in a chain" of evidence tending to establish guilt of a criminal offense; in ruling upon a claim of privilege, the trial court must find that it clearly appears from a consideration of all the circumstances in the case that an answer to the challenged question cannot possibly have a tendency to incriminate the witness. ( Hoffman v. United States, 341 U.S. 479, 486-488 [95 L.Ed. 1118, 1123-1125, 71 S.Ct. 814]; Malloy v. Hogan, supra, 378 U.S. 1, 11-12 [12 L.Ed.2d 653, 661-662]; Zonver v. Superior Court, 270 Cal.App.2d 613, 620 [ 76 Cal.Rptr. 10]; Cohen v. Superior Court, 173 Cal.App.2d 61, 68-70 [ 343 P.2d 286]; Evid. Code, § 404.)

(1b) Applying the foregoing test to the discovery order in the instant case, neither the order nor the record below enables us to say that it clearly appears that disclosure to the prosecution of the names, addresses and expected testimony of petitioner's witnesses cannot possibly tend to incriminate her. Unlike the situation in Jones, the order herein is not limited to any particular defense or category of witnesses from which a court could attempt to determine its incriminatory effect. It requires no great effort or imagination to conceive of a variety of situations wherein the disclosure of the expected testimony of defense witnesses, or even their names and addresses, could easily provide an essential link in a chain of evidence underlying the prosecution's case in chief.

For example, if a defendant in a murder case intended to call witness A to testify that defendant killed in self-defense, pretrial disclosure of that information could provide the prosecution with its sole eyewitness to defendant's homicide. Similarly, consider the effect of disclosing the name or expected testimony of witness B, whom defendant intends to call only as a "last resort" to testify that defendant only committed a lesser-included offense.

Thus the order before us is too broad, for it could require petitioner to disclose information which might serve as a link in a chain of evidence tending to establish her guilt of a criminal offense. In ruling upon petitioner's claim of privilege, the trial court failed to inquire into the incriminatory nature of the information sought, acting upon the assumption that Jones and Pike authorized disclosure without regard to possible incriminatory effect. Since the order was for this reason violative of petitioner's constitutional rights, it was beyond the court's jurisdiction and therefore void and unenforceable.

We do not intend to suggest that the prosecution should be barred from any discovery in this, or any other, case. A reasonable demand for factual information which, as in Jones, pertains to a particular defense or defenses, and seeks only that information which defendant intends to introduce at trial, may present no substantial hazards of self-incrimination and therefore justify the trial judge in determining that under the facts and circumstances in the case before him it clearly appears that disclosure cannot possibly tend to incriminate defendant. However, unless those criteria are met, discovery should be refused.

Let a peremptory writ of prohibition issue restraining respondent court from enforcing its discovery order herein.

Mosk, Acting C.J., McComb, J., Tobriner, J., and Peek, J., concurred.