¶1(concurring). I agree with that portion of the majority opinion dealing with the burden of proof issue. “There is no requirement that the state show beyond a reasonable doubt that the informer’s testimony would not be helpful to the defense.” Supra, at 127.
¶2*139I emphatically disagree with that portion of the majority opinion which establishes the scope of review of a trial judge during an in camera hearing: “We conclude that the proper test is whether the testimony the informer could have given was relevant and admissible in respect to an issue material to the accused’s defense and, hence, was reasonably necessary to a fair determination of guilt or innocence.” Supra, at 132. I do not believe that relevant and admissible in respect to an issue material to the accused’s defense is the equivalent of reasonably necessary to a fair determination of guilt or innocence.
¶3Sec. 905.10(3) (b), Stats., clearly specifies that after an in camera inquiry the trial judge determines if there is a reasonable probability that the informer can give testimony “necessary to a fair determination of the issue of guilt or innocence in a criminal case.” (Emphasis added.) The statute does not use the words “admissible,” “relevant,” or “helpful.” As I see it, there is a significant difference between these terms; something may be relevant and admissible, but not necessary.. Only if an informant’s testimony is necessary to a fair trial will the informer’s privilege give way. Although federal cases use the language relevant and helpful, the majority has correctly noted that “federal authorities are not of controlling precedential significance.” Supra, at 121. The majority also correctly states: “[T]he Wisconsin [informer’s privilege] rule is distinctly a product of Wisconsin Supreme Court rule making.” Supra, at 120.
¶4Although sec. 905.10(3) (b), Stats., does not define “necessary,”
¶5In my opinion, the informer’s testimony, revealing that he could not positively identify the defendant, “could have created in the minds of the jurors a reasonable doubt” regarding the defendant’s guilt. Accordingly, the trial judge abused his discretion in failing to compel disclosure of the informer’s identity.
¶6The trial court was not in error in following that portion of the direction of the court of appeals which required disclosure only if it were helpful to the defense. The court of appeals construed sec. 905.10(3) (b), Stats., to require disclosure only if the informer’s testimony were found to be relevant and helpful to the defense. The “relevant and helpful” terminology ignores the language of the statute denominating “necessary to a fair determination of guilt or innocence” as the proper standard. A rational interpretation of this language does not require the conclusion that the informer’s identity be disclosed to the defendant if it is probative only of the guilt of the defendant.
¶7Following the reasoning of the majority opinion, a defendant need only convince the judge that the informer has information which is relevant and admissible in respect to an issue material to the accused’s defense. If the in camera inquiry results in the judge concluding the *141informer can positively identify the defendant, such testimony meets the test enunciated by the majority. I would limit the test to evidence being necessary to support the theory of the defense. Therefore, where identification is at issue, I would declare the evidence is not necessary to the theory of mistaken identity where the informer can identify the defendant with reasonable certainty as the participant in criminal activity. In the instant case, the trial judge was not faced with such a situation and made his determination on other grounds, but I set forth this possible situation to identify the need to limit the test. A defendant who knows the available evidence of his guilt is overwhelming may insist upon disclosure of the informer’s identity solely as a retaliatory move or in the interests of his peers in order to thwart the informer’s effectiveness in the future.
¶8This limitation is essential because it “is well to remember that the illegal traffic in narcotic drugs poses a most serious social problem .... No crime leads more directly to the commission of other offenses. Moreover, it is a most difficult crime to detect and prove .... Enforcement is, therefore, most difficult without the use of . . . informants .... To give [informants] protection governments have always followed a policy of nondisclosure of their identities.Of course where enforcement of a nondisclosure policy deprives cun accused of a fair trial it must either he relaxed or the prosecution must he foregone.” Roviaro v. United States, 353 U.S. at 66-67 (Clark, J. dissenting) (emphasis added).
¶9I specifically reject that language in the majority opinion stating the proper test for disclosure of an informer’s identity to be whether the informer’s testimony was relevant and admissible to a material issue. I conclude that an essential condition precedent to disclosure is that the informer’s testimony be necessary to the defense. Furthermore, when nondisclosure deprives an accused of a fair trial, when indeed disclosure is neces*142sary as it could create a reasonable doubt of the defendant’s guilt in the jurors’ minds, then and only then should this important privilege give way.
¶10I am authorized to state that Justices Day, Steinmetz, and Ceci, join in this concurring opinion.
¶11 Necessary, by common dictionary definition means “essential,” “indispensable,” “absolutely required,” “that [which] cannot be done without.” Webster’s Third International Dictionary, 1510-11 (1966). As I interpret sec. 905.10(3) (b), Stats., only if an informer’s testimony is essential or indispensable must the informer’s identity be compelled. See Stelloh v. Liban, 21 Wis. 2d 119, 126, *140124 N.W.2d 101 (1963), where we noted that the American Law Institute, Model Code of Evidence, Rule 230 at 168, provides that the identity of an informer should be disclosed if it “is essential to assure a fair determination of the issues.” (Emphasis added.) See also Roviaro v. United States, 353 U.S. 53, 61 (1957) (“essential to a fair determination of a cause”).