The defendant was indicted in February, 1981, for murder, and a trial is pending. In September, 1981, he applied for relief under G. L. c. 211, § 3, asking this court to revoke the immunity of a witness who will testify against him. A single justice denied relief, and the defendant appealed to the full court. We conclude that the defendant has no standing to challenge the grant of immunity, and is entitled to no relief.
A young woman named Doreen Levesque was murdered in October, 1979. Another young woman, Karen Marsden, was murdered in February, 1980. Police records and grand jury minutes reproduced in the record indicate that these murders were among a series of ritual killings performed in the Fall River area by members of a Satanic cult. The defend*346ant, William Smith, is charged with participation in the first of the murders named above, that of Doreen Levesque.
The witness in question is Robin Murphy. In the spring of 1980, police received information connecting Robin Murphy to the Levesque and Marsden murders. Murphy was interrogated, and admitted that she had been involved.1 She described the practices of the Satanic cult and indicated that both victims had been connected with the cult, either as devotees of the faith or as associates in a prostitution enterprise. She also gave a rather vague description of “Willie,” whom she named as a participant in the Levesque murder.
In May, 1980, a grand jury indicted Robin Murphy and others for the murder of Karen Marsden. On January 14, 1981, Murphy pleaded guilty to murder in the second degree.2
On January 16, 1981, Murphy appeared as a witness before a grand jury investigating a possible conspiracy to murder Karen Marsden.3 She was asked several questions about the planning and execution of the Marsden murder, but was not asked specifically about the Levesque murder. In response to all questions, she invoked her right to remain silent, as guaranteed by the Fifth Amendment to the United States Constitution.
*347On February 9, 1981, the Commonwealth applied to a single justice of this court for an order of immunity for Robin Murphy. G. L. c. 233, §§ 20C-20E, 20G, inserted by St. 1970, c. 408.4 In its application, the Commonwealth stated its belief, based on conversations with Murphy, that the conspiracy to murder Karen Marsden was inspired in part by Marsden’s knowledge of the Levesque murder. The single justice issued an order of immunity specifically covering “the transactions surrounding the death[s] of Doreen Levesque and Karen Marsden.”
On February 17, 1981, Murphy testified before a grand jury investigating the defendant’s role in the murder of Doreen Levesque.5 She described the ritual that accompanied the murder, and named various participants. She also recited that in a previous photographic identification procedure she had identified William Smith (the defendant) as “Willie,” one of the persons present at the murder. She then described in some detail Willie’s part in the killing. Murphy later appeared at the trials of other defendants, and she testified about both the Marsden and Levesque murders. She has since denied, and then reaffirmed, the truth of her testimony.
*348The defendant contends that the grant of immunity to Robin Murphy did not conform to the authorizing statute, G. L. c. 233, §§ 20C-20E, 20G, and asks that we exercise our extraordinary powers of superintendence under G. L. c. 211, § 3, to nullify the immunity. He points, in rather obscure fashion, to at least three perceived defects in the immunity order. First, he argues that the order should not have covered the murder of Doreen Levesque, because the witness Murphy had not asserted her privilege against self-incrimination specifically with respect to that murder. Second, he claims that the immunity did not adequately protect the witness, because she was only sixteen at the time of the Levesque murder, and so was amenable to delinquency charges, which are not mentioned in the immunity statute.6 See G. L. c. 233, § 20D. Finally, the defendant appears to object to the fact that the witness had pleaded guilty to the murder of Karen Marsden, and was serving a prison sentence. We express no opinion on the merits of these arguments, because the defendant has not made a threshold showing that he is entitled to relief under G. L. c. 211, § 3.
A defendant seeking interlocutory relief under G. L. c. 211, § 3, must allege a violation of a personal, substantive right, and his claim must be substantial. He must also show that unless interlocutory relief is granted, irreversible harm will follow. Costarelli v. Commonwealth, 374 Mass. 677, 679-680 (1978). Gilday v. Commonwealth, 360 Mass. 170, 171 (1971). The defendant’s application fails to meet this test for a number of reasons, the most obvious of which is that he has no standing to press the arguments he raises.7
*349We have held, without qualification, that a defendant “has no standing to argue that the testimony of . . . purportedly immunized witnesses [is] the product of improper grants of immunity.” Commonwealth v. Simpson, 370 Mass. 119, 121 (1976) (Superior Court had not followed statutory procedures for immunity order). Accord, United States v. Ellis, 595 F.2d 154,163 (3d Cir.), cert. denied, 444 U.S. 838 (1979); United States v. Hathaway, 534 F.2d 386, 402 (1st Cir.), cert. denied, 429 U.S. 819 (1976); United States v. Braasch, 505 F.2d 139, 146 (7th Cir. 1974), cert. denied, 421 U.S. 910 (1975); United States v. Leonard, 494 F.2d 955, 972-973 (D.C. Cir. 1974); United States v. Lewis, 456 F.2d 404, 408-410 (3d Cir. 1972); Lopez v. Burke, 413 F.2d 992, 994 (7th Cir. 1969). But cf. Ellis v. United States, 416 F.2d 791, 798-800 (D.C. Cir. 1969). This rule is supported by sound reasons. The privilege against self-incrimination is a personal right of the witness, and one that the witness is in a position to protect by his own means. Commonwealth v. Simpson, supra. Goldstein v. United States, 316 U.S. 114, 121 n.11 (1942). Moreover, the statutory procedure for a grant of immunity is designed to accommodate the witness’s rights and the State’s need for evidence. The statute is simply not addressed to the interests of defendants.8
The defendant, apparently seeking an exception to the established rule, suggests that the immunity order affects him personally. He argues first, because the order covers two transactions, the witness is forced to adhere to her original “immunity story”9 in a series of proceedings, including those against him. He also contends that because the witness was in prison when she was immunized and will remain in prison through the defendant’s trial, she is likely *350to be influenced by State authorities, and unlikely to fear a sentence for perjury. These circumstances, the defendant argues, detracted from the integrity of the grand jury that indicted him, and will deprive him of basic fairness and effective assistance of counsel at trial. He also argues that the order was “imprecise,” and that its imprecision prevents him from exposing by cross-examination its effect on the witness.
The defects that the defendant perceives in the witness’s testimony have no relation to the terms of her immunity. The witness’s obligation to testify consistently in successive proceedings arises from the laws with respect to perjury. The possibility that she is biased in favor of the Commonwealth is an unavoidable incident of her status as a prisoner and her desire for parole. Moreover, the various constraints on the witness are matters of credibility. They can be explored fully on cross-examination, and we find nothing “imprecise” in the order that might frustrate the defendant’s examination of the witness.10
In sum, the defendant has not established that the grant of immunity to Robin Murphy affected him in any way other than making available her testimony against him. The cases the defendant cites in support of his standing are inap-posite.11 There is no cause for an exception to the rule that a defendant lacks standing to challenge a witness’s immunity, and no grounds for relief under G.L.c. 211, §3. The order of the single justice is therefore affirmed.
So ordered.