OPINION

NEWMAN, J.

The People appeal an order suppressing evidence (Pen. Code, § 1538.5, subd. (a)) and a judgment dismissing a criminal information ( id., § 995). The information charged defendant with possession of cocaine (Health Saf. Code, § 11350) and of marijuana for sale ( id., § 11359). We inquire whether a search warrant affidavit was deficient because it omitted information bearing on the credibility of an undisclosed informant. We conclude that the omissions asserted did not make the affidavit substantially misleading. Accordingly we reverse the judgment of dismissal and the order suppressing evidence.

On April 6, 1976, Officers Bell and Matt of the Modesto Police Department obtained a warrant to search Kurland's Discount Water Beds, a store owned by defendant, for cocaine, paraphernalia, and evidentiary documents. The search, carried out the same day, disclosed a "coke" spoon and vial of white powder in defendant's pocket. Defendant handed the searching officers a baggie of marijuana and some "zigzag" cigarette papers from "my" briefcase. Two other containers of marijuana and a .38 caliber pistol were found in his office. The marijuana weighed a pound and a half; the white powder in the vial proved to be cocaine.

The warrant was principally supported by Matt's affidavit. It declared in substance that Z, a confidential informant proved reliable in two earlier narcotics cases, had told Matt he frequently and recently saw defendant, at the store, in possession of substantial quantities of described substances. Z believed and defendant had confirmed that these were cocaine and marijuana. Defendant had confided to Z his storage and sale of narcotics. He told Z he sometimes used "Steve's" house, behind his own, to keep contraband. Z had recently seen marijuana in Steven Mendes' residence behind defendant's home. Z also had recently seen a .38 caliber pistol on defendant's desk at the store. Defendant told Z he intended to kill, or have killed, the next person who crossed him. Defendant had asked Z to kill someone who had "ripped him off" in a drug deal.

The affidavit recited Matt's confirmation that the addresses given by Z were occupied by defendant and Mendes. Matt also alleged he had seen defendant pick up a concealed weapon permit application and had overheard defendant tell the clerk that it was for a .38 caliber pistol. A completed application was never submitted. According to the affidavit, Z's statements about use of "Steve's" residence to keep narcotics conformed to Matt's experience about the habits of drug dealers. The affidavit disclosed that Z was a former user of cocaine, was familiar with its packaging and use, was continuing to serve as a narcotics informant, and had never given false information. Finally the affidavit told why Matt feared for Z's safety if his identity were disclosed.

At the suppression hearing, despite the People's repeated objections on grounds of protecting a confidential source, defense counsel examined Matt about his relation with Z. The answers revealed that Z had been convicted of a felony after Matt signed a 1974 complaint against him, that Z had been placed on probation, that Matt had a dozen contacts with Z in 1976, and that Matt and Z had discussed Z's cooperation as an informant. Matt also testified he did not know when he prepared the affidavit whether Z's probation had been terminated or whether Z had violated probation. Matt denied that threats were made to Z to induce his cooperation against defendant. Questions about the nature of the offenses charged in 1974 and whether Matt was then the investigating officer were never answered in open court. Some additional details were revealed in in camera hearings convened by the court to resolve the People's confidential-source objections.

The court granted defendant's motion to suppress on the ground that "material information" was not disclosed in the affidavit which might have led the magistrate "to conclude differently in respect to the credibility of the confidential informant." The information was then dismissed.

The People say that the affidavit was not misleading and that the disputed information was withheld properly and in good faith on grounds of privilege. Therefore we must decide what rules apply when defendant charges that a warrant affidavit, though sufficient on its face, is incomplete.

1. May defendant show omission from the affidavit?

(1) In California a facially valid search warrant affidavit may be attacked on grounds that it contains deliberate or negligent misstatements. The rule arises both from our Constitution's guarantee against unreasonable search and seizure and from statutes regarding suppression of illegally obtained evidence. (Cal. Const., art. 1, § 13; Pen. Code, §§ 1538.5-1540; People v. Cook (1978) 22 Cal.3d 67, 74 [ 148 Cal.Rptr. 605, 583 P.2d 130]; Theodor v. Superior Court (1972) 8 Cal.3d 77, 100-101 [ 104 Cal.Rptr. 226, 501 P.2d 234].) It rests upon the constitutional preference for warrants, which presupposes that probable cause determinations will be made independently by neutral, fully informed judicial officers rather than by the police. A misinforming affidavit hinders the magistrate's inference-drawing powers and increases the likelihood that privacy will be invaded without probable cause. ( Cook, supra, 22 Cal.3d at pp. 81-82; see Aguilar v. Texas (1964) 378 U.S. 108, 110-111 [12 L.Ed.2d 723, 726, 84 S.Ct. 1509]; Johnson v. United States (1948) 333 U.S. 10, 13-14 [92 L.Ed. 436, 440, 68 S.Ct. 367]; Theodor, supra, 8 Cal.3d at pp. 90-91, fn. 6, 96.)

This court in Theodor recognized that similar difficulties might arise when an affidavit simply fails "to include information which might otherwise negate a finding of probable cause." (8 Cal.3d at p. 96, fn. 11; see also Cook, supra, 22 Cal.3d at p. 92.) The Courts of Appeal have consistently held that an affidavit may be insufficient when it omits facts adverse to the warrant application. ( People v. Neusom (1977) 76 Cal.App.3d 534, 538-539 [ 143 Cal.Rptr. 27]; Morris v. Superior Court (1976) 57 Cal.App.3d 521, 526 [ 129 Cal.Rptr. 238]; People v. Barger (1974) 40 Cal.App.3d 662, 668-669 [ 115 Cal.Rptr. 298]; see People v. Webb (1973) 36 Cal.App.3d 460, 470-471 [ 111 Cal.Rptr. 524].)

(2) Now directly faced with the issue, in general we endorse those holdings. An affidavit may be as inaccurate when it omits facts as when it misstates them. The crucial, inference-drawing powers of the magistrate may be equally hindered in either case, with identical consequences for innocent privacy. (See Moylan, Hearsay and Probable Cause: An Aguilar and Spinelli Primer (1974) 25 Mercer L.Rev. 741, 749.) We therefore conclude that the California Constitution and statutes permit defendant to attack a facially sufficient warrant affidavit on grounds that, though it contains no affirmative falsehoods, it is incomplete.

2. What facts must affiant include?

Though similar for many purposes, omissions and misstatements analytically are distinct in important ways. Every falsehood makes an affidavit inaccurate, but not all omissions do so. (3) An affidavit need not disclose every imaginable fact however irrelevant. It need only furnish the magistrate with information, favorable and adverse, sufficient to permit a reasonable, common sense determination whether circumstances which justify a search are probably present. (See United States v. Harris (1971) 403 U.S. 573, 577-585 [29 L.Ed.2d 723, 730, 91 S.Ct. 2075]; Spinelli v. United States (1969) 393 U.S. 410, 419 [21 L.Ed.2d 637, 645, 89 S.Ct. 584]; United States v. Ventresca (1965) 380 U.S. 102, 108 [13 L.Ed.2d 684, 688-689, 85 S.Ct. 741]; People v. Stout (1967) 66 Cal.2d 184, 192-193 [ 57 Cal.Rptr. 152, 424 P.2d 704].)

Recognizing this, the Courts of Appeal seem consistently to have held that an affiant's duty of disclosure extends only to "material" or "relevant" adverse facts. At the same time, they have applied the materiality requirement to reach only those omissions which significantly distorted the probable cause analysis. (See Neusom, supra, 76 Cal.App.3d at p. 541; Morris, supra, 57 Cal.App.3d at p. 527; Barger, supra, 40 Cal.App.3d at pp. 668-669; Webb, supra, 36 Cal.App.3d at p. 470.)

We think the results reached by these decisions strike a proper balance among practicality, accuracy, and the policy of encouraging resort to the warrant process. (See Ventresca, supra, 380 U.S. at pp. 106, 108 [13 L.Ed.2d at pp. 687, 688-689]; People v. Keener (1961) 55 Cal.2d 714, 723 [ 12 Cal.Rptr. 859].) (4) We conclude, as Courts of Appeal effectively have concluded, that facts are "material" and hence must be disclosed if their omission would make the affidavit substantially misleading. On review under section 1538.5, facts must be deemed material for this purpose if, because of their inherent probative force, there is a substantial possibility they would have altered a reasonable magistrate's probable cause determination.

The People urge that, even if Officer Matt intentionally omitted material facts, the warrant evidence should not be suppressed because the omissions were proper, or at least reasonable and in good faith. Defendant argues, on the other hand, that suppression is the proper remedy whenever material facts are intentionally or deliberately excluded. We must therefore decide what remedies apply when omissions from the affidavit are found.

3. What are the remedies for an incomplete affidavit?

Theodor recognized that all inaccuracy in the affidavit impedes the neutral determination of probable cause. However, it concluded, probability and not certainty is the relevant standard; and constitutional protections against unlawful search and seizure are subject to "the overriding principle of reasonableness. . . ." Negligence by an affiant should be deterred, but reasonable attempts at accuracy should be accepted. (8 Cal.3d at pp. 96-97.) Thus, the court held, where affiant reasonably believed his statements the warrant should stand. When he was not reasonable in believing them, they should be excised and the remaining allegations retested for probable cause. ( Id., at pp. 100-101.)

In Cook, we considered the appropriate sanction for reckless or knowing falsehoods. We explained why mere negligence calls for the "correct and retest" device, rather than quashing of the warrant. Negligent falsehood, we reasoned, does not undermine the magistrate's conclusion that affiant was generally credible. Hence the remaining statements in the affidavit may be presumed true and their sufficiency retested by a reviewing court under section 1538.5. But lying or reckless inaccuracy may render the truthfulness of all statements in the affidavit suspect. The reviewing court independently cannot reassess the affiant's credibility, since that is a matter exclusively for the magistrate. It therefore lacks a "reliable factual basis" to determine probable cause. There remains in such cases no alternative but to quash the warrant. (22 Cal.3d at pp. 84-87.)

Cook expressly reaffirmed the "rule of reason," holding that the exclusionary doctrine developed in Theodor is intended, by deterring unlawful police conduct, to minimize the risk that innocent privacy will be invaded. Once unlawful conduct is shown, Cook explained, the scope of the exclusionary rule will depend on whether the inaccuracy was negligent, on the one hand, or reckless or deliberate on the other. But if the affidavit reflects a reasonable attempt at truth, constitutional principles are satisfied; and no purpose is served by vitiating the warrant, no matter how crucial the inaccuracy. (22 Cal.3d at pp. 82-88.) We adhere to that analysis here.

Theodor and Cook described misstatements as "reasonable," "negligent," and "intentional," applying the exclusionary rule accordingly. By analogy, the Courts of Appeal have held that material facts "negligently" omitted must be added to the affidavit by the reviewing court and the affidavit then retested for probable cause. "Intentional" omissions of material facts have been deemed to require an automatic quashing of the warrant. ( Barger, supra, 40 Cal.App.3d 662, 669; Neusom, supra, 76 Cal.App.3d 534, 538-539; Morris, supra, 57 Cal.App.3d 521, 527-528.)

Defendant contends that, under Theodor and Cook, negligence is synonymous with inadvertence and that every conscious omission of a material fact, no matter how reasonable or justified, should invoke the sanction of suppression. We disagree.

Both defendant and lower courts have failed to realize that the Theodor-Cook system of remedies may not be applied exactly to omissions. Unlike misstatements, omissions do not always render an affidavit inaccurate. As we have seen, only material omissions have that effect. Intentional omissions, unlike the intentional misstatements considered in Cook, are not necessarily an effort to mislead the magistrate. (5) (See fn. 5.) They may arise from a correct, or at least reasonable, conclusion that the omitted facts were immaterial or privileged. The procedures and remedies applicable to omissions must account for those crucial differences.

(6a) First, the reviewing court must determine whether any omissions asserted are material, as herein we have defined that term. Because an affidavit with no material omissions is substantially accurate and truthful, it corresponds for most purposes to an affidavit with no misstatements. Once all the asserted omissions have been deemed immaterial, the primary question is whether the affidavit on its face supports probable cause. If it does, the warrant usually must stand. (See, e.g., People v. Neusom, supra, 76 Cal.App.3d at p. 541; People v. Webb, supra, 36 Cal.App.3d at p. 470; but see discussion, post.)

(7), (8) If an omission is found material, the reviewing court must next determine, as in Theodor and Cook, whether it arose innocently or from culpable conduct. However, since not all intentional omissions of material facts are blameworthy, the reviewing court must apply a modified version of the Theodor-Cook formula for culpability. The necessary modification is plain. The trial court must decide whether the material omission was either (1) reasonable, (2) negligent, or (3) recklessly inaccurate or intentionally misleading. That the omission itself was "intentional" rather than inadvertent may be relevant to those issues, but may not alone be dispositive.

A material omission is reasonable when despite the exercise of due care, affiant was ignorant of the omitted fact or forgot to include it, or his conclusion that it was privileged or immaterial was reasonable even if incorrect. Where material omissions are reasonable, whether volitional or inadvertent, no sanction should be imposed; the situation corresponds to that of reasonable misstatements. Because affiant will, in such cases, have done all that can reasonably be expected to comply with constitutional standards, little deterrent purpose would be served by further review of the affidavit. ( Theodor, supra, 8 Cal. 3d at pp. 97-100.)

Negligent omissions of material fact occur when the affiant is unreasonably ignorant of facts, unreasonably forgets to include them, or makes a good faith but unreasonable decision that they need not or should not be included. In such cases the "add and retest" formula developed in Barger, Morris, and Neusom is proper. It discourages carelessness and helps eliminate the likelihood that a negligent mistake may cause an erroneous finding of probable cause. Yet it recognizes the affiant's good faith effort at accuracy. ( Cook, supra, 22 Cal.3d at pp. 84-85.)

The dissent here suggests that any intentional material omission should automatically vitiate the warrant. As with intentional misstatements, it argues, deliberate omission of a material fact undermines the magistrate's implicit finding that the affiant was credible and deprives the reviewing court of a "reliable factual basis" to redetermine probable cause. (See Cook, supra, 22 Cal.3d at pp. 86-87.) We disagree.

An intentional omission is not necessarily culpable. Moreover, an omission can be both intentional and negligent at the same time. Thus an intentional omission, even where material, should not automatically invoke Cook's "suspect-credibility" reasoning, though a deliberate lie properly does. Something more than mere intent to omit is required to justify the conclusion that statements that do appear in the affidavit may not be trusted.

The dissenting opinion here suggests that a reviewing court may not assume the magistrate would have found probable cause had he known of the negligent omission. Hence, the dissent reasons, an affidavit materially incomplete because of affiant's negligence may never support a decision to uphold the warrant. That view contravenes both Theodor and Cook.

Every negligent inaccuracy, whether misstatement or substantial omission, might have induced a fully informed magistrate to find probable cause lacking. Yet nothing in our recent cases suggests that the court therefore must quash the warrant. On the contrary, the reviewing court simply eliminates the negligent inaccuracy, assumes the affidavit to be otherwise truthful, and determines independently whether, as corrected, the affidavit is "sufficient, under settled standards, to [establish] probable cause. . . ." ( Theodor, supra, 8 Cal.3d at p. 101, fn. 14; Cook, supra, 22 Cal.3d at pp. 84-85.)

That "rule of reason" assumes, as does the dissent, that the reviewing court may not second-guess the magistrate. ( Cook, supra, at p. 85.) However, it also recognizes that we do not minimize unreasonable invasions of privacy by rejecting, on review, the entire showing of a credible affiant because negligently he or she was inaccurate in one respect. ( Ibid.) Moreover, it encourages the affiant to inform the magistrate fully by extending the duty of disclosure in the affidavit beyond those facts that necessarily would preclude a finding of probable cause.

The dissent urges that an "add and retest" remedy for negligent omissions is an insufficient sanction to deter improper police conduct. Such a view ignores the express holding of Theodor, so recently confirmed in Cook, that negligent inaccuracy calls only for correction and retesting. ( Theodor, 8 Cal.3d at pp. 100-101; Cook, 22 Cal.3d at pp. 82-85.)

Indeed, the rule espoused would frustrate rather than promote the deterrent goals of those decisions. It would contravene the principle of reasonable accuracy, under which mistakes occurring despite the exercise of due care are not punished, however crucial. ( Theodor, 8 Cal.3d at pp. 97-101; Cook, 22 Cal.3d at p. 82.) And because it would not leave a sterner sanction for deliberate attempts to mislead the magistrate (see discussion, post), the police would have nothing to lose by sliding from mere carelessness into recklessness and treachery.

(6b), (9) When an abuse of that gravity appears — when affiant intentionally omits any fact for the purpose of deceiving the magistrate or recklessly disregards the accuracy and completeness of the affidavit — Cook's analysis fully applies. An omission of that kind is no different from a reckless falsehood or a deliberate lie. Any such attempt to mislead the magistrate undermines the judicial process, makes the entire affidavit suspect, and calls for harsh deterrence. The appropriate response is to quash the warrant regardless of whether the omission ultimately is deemed material.

(10), (11) The burden on the issues of materiality, privilege, and affiant's culpability is to be allocated as in the case of misstatements. If the defense states "with some specificity" its reasons for believing that material facts were omitted, it may try to show such omissions and their materiality. The obligation of showing that material omissions were proper or reasonable rests with the People, but defendant has the burden of demonstrating recklessness or intent to mislead. (See Cook, supra, 22 Cal.3d at pp. 89-92; Theodor, supra, 8 Cal.3d at p. 102.)

We are aware of Cook's holding that defendant need not show bad faith or ulterior motive to quash a warrant for deliberate falsehood, since "[t]hat would indeed be a difficult burden to sustain. . . ." (22 Cal.3d at p. 91.) But Cook also reasoned that such a showing was "of little if any relevance: once the defendant has shown the affiant knowingly lied under oath in any respect, the remainder of his allegations become suspect regardless of what his ulterior motives may have been. . . ." ( Ibid., italics added.)

In other words, perjury is sufficient evidence of lack of credibility; and proof of an ulterior motive for the lie is redundant. But intentional omissions do not necessarily have the same effect. There must be something more that gives an intentional omission the culpable quality of perjury. An intent to mislead supplies the element of purposeful deception already implicit in lying.

Demonstrating purposeful deception may be a difficult burden, but we do not think it is an insurmountable one. "It may be evidenced by the affirmative statement or admission" of affiant. "If he is silent or [denies a purpose to mislead]" it may be shown indirectly. ( Id., at p. 90.) For example, if affiant denies knowledge of omitted facts his protestations may be overcome by the testimony of those present when he learned them. If he says he did not disclose the facts because he thought they were privileged or immaterial, the evidence may permit an inference that no such belief could have arisen in good faith. The more unreasonable the circumstances surrounding an omission, the more compelling the inference of recklessness or intentional deception.

If defendant can show why the affiant sought to deceive — his ulterior motive — he certainly may do so to bolster his circumstantial case. Yet such an inquiry often will be unnecessary under the standard we adopt.

All issues necessary to determine the warrant's validity are to be resolved in the first instance by the trial court at the suppression hearing. Here the court did not make the necessary determinations. It suppressed the warrant evidence simply on grounds that the omissions were material and volitional. Issues of privilege, negligence, recklessness, and intentional deception never were resolved. On that ground alone, the suppression order and the consequent judgment of dismissal must be reversed.

4. Were the omissions material?

Long settled law already creates a strong inference that information from police contacts is to be viewed with extreme caution. An affidavit which relies on information from a tipster must set forth underlying facts justifying the conclusion that the source is reliable or the information itself credible. ( Aguilar v. Texas, supra, 378 U.S. 108, 114 [12 L.Ed.2d 723, 728-729]; Alexander v. Superior Court, supra, 9 Cal.3d 387, 393.) An affiant's conclusory opinions of reliability or credibility are not enough, and mere quantity and detail in the tipster's statements do not render them worthy of belief. ( People v. Scoma (1969) 71 Cal.2d 332, 340 [ 78 Cal.Rptr. 491, 455 P.2d 419].) Reliability must be shown independently, as by corroboration of the information received ( Spinelli v. United States, supra, 393 U.S. 410, 417-418 [21 L.Ed.2d 637, 644]; Alexander, supra, 9 Cal.3d at p. 395), the informant's previous record of accuracy in similar situations ( Jones v. United States (1960) 362 U.S. 257, 270-271 [4 L.Ed.2d 697, 707-708, 80 S.Ct. 725, 78 A.L.R.2d 233]), or indications that the informant has spoken against penal interest. ( United States v. Harris, supra, 403 U.S. 573, 583 [29 L.Ed.2d 723, 734].) If the affidavit includes insufficient details to permit a reasonable belief in probable accuracy, it fails to demonstrate probable cause as a matter of law.

The rule that the affiant must demonstrate a tipster's probable reliability or credibility arises not only from the usual distrust of hearsay evidence but also from an assumption that information provided by customary police sources is inherently suspect. Accordingly, the rule does not apply to information from disinterested citizens who accidentally observe crime and report it forthrightly as a civic duty. "Citizen informants," once identified as such, are presumptively reliable. (E.g., People v. Smith (1976) 17 Cal.3d 845, 850-851 [ 132 Cal.Rptr. 397, 553 P.2d 557]; People v. Ramey (1976) 16 Cal.3d 263, 269, and fn. 4 [ 127 Cal.Rptr. 629, 545 P.2d 1333]; People v. Hill (1974) 12 Cal.3d 731, 761 [ 117 Cal.Rptr. 393, 528 P.2d 1], disapproved on other grounds, People v. DeVaughn (1977) 18 Cal.3d 889, 896 [ 135 Cal.Rptr. 786, 558 P.2d 872]; Krauss v. Superior Court (1971) 5 Cal.3d 418, 421-422 [ 96 Cal.Rptr. 455, 487 P.2d 1023], disapproved on other grounds, Cook, supra, 22 Cal. 3d at pp. 98-99; People v. Guidry (1968) 262 Cal.App.2d 495, 497-498 [ 68 Cal.Rptr. 794]; People v. Lewis (1966) 240 Cal.App.2d 546, 549-550 [ 49 Cal.Rptr. 579].)

In Smith the court explained that distinction by quoting this succinct statement in People v. Schulle (1975) 51 Cal.App.3d 809, 814-815 [ 124 Cal.Rptr. 585]: "A 'citizen-informant' is distinguished from a mere informer who gives a tip to law enforcement officers that a person is engaged in the course of criminal conduct. [Citations.] Thus, experienced stool pigeons or persons criminally involved or disposed are not regarded as 'citizen-informants' because they are generally motivated by something other than good citizenship. [Citations.]" ( Smith, supra, 17 Cal.3d at pp. 850-851; italics added.)

Such persons frequently have criminal records and a history of contact with the police. Often they are free only on probation or parole or are themselves the focus of pending criminal charges or investigations. All familiar with law enforcement know that the tips they provide may reflect their vulnerability to police pressure or may involve revenge, braggadocio, self-exculpation, or the hope of compensation. (See United States v. Harris, supra, 403 U.S. 573, 599 [29 L.Ed.2d 723, 742-743] [dis. opn. of Harlan, J.]; United States v. Gonzalez (5th Cir. 1974) 491 F.2d 1202, 1207-1208; United States v. Unger (7th Cir. 1972) 469 F.2d 1283, 1287, cert. den. (1973) 411 U.S. 920 [36 L.Ed.2d 313, 93 S.Ct. 1546]; United States v. Kinnard (D.C. Cir. 1972) 465 F.2d 566, 570; People v. Hambarian (1973) 31 Cal.App.3d 643, 655 [ 107 Cal.Rptr. 878]; People v. Cheatham (1971) 21 Cal.App.3d 675, 677, fn. 2 [ 98 Cal.Rptr. 670]; Moylan, supra, 25 Mercer L.Rev. at pp. 769-779.) The details of their criminal pasts are not necessary to place the magistrate on notice of their potential unreliability. ( People v. Webb, supra, 36 Cal.App.3d 460, 470.)

Both an issuing magistrate and a reviewing court must initially assume that information from such sources is unreliable for purposes of probable cause. Such a rule alerts the magistrate to the very danger defendant urges — that the statements of tipsters from "criminal society" may receive unwarranted weight.

(13a) We therefore conclude that, in most cases, the issue of possible unreliability is adequately presented to the magistrate when the affidavit reveals that the affiant's source of information is not a "citizen-informant" but a garden-variety police tipster. In such circumstances, predictable details of the informer's criminal past will usually be cumulative and therefore immaterial.

Here, Matt's affidavit made clear that Z was not a citizen-informant. It recited that Z had supplied narcotics information in the past, was himself a former user of hard drugs, and was continuing to operate as a confidential police source. It detailed his association not only with defendant but with Steven Mendes, who the informant believed was also involved in narcotics. Thus Z was clearly identified as a more-or-less-regular police agent, useful for his drug connections; and the magistrate was alerted to draw adverse conclusions about Z's reliability.

The details of Z's past revealed at the open suppression hearing would have added little to the magistrate's deliberations. Essentially they showed that Matt's efforts had contributed to Z's felony conviction, that Z was on probation, and that Z and Matt had discussed Z's cooperation as an informant. Even if those facts might support an inference of Z's dishonesty or vulnerability to police pressure, that inference was already inherent in Z's status as a confidential tipster. The omitted details provided no extraordinary indication that Z's information in this particular case was unreliable.

Defendant argues in particular that Z's 1974 felony conviction for receiving stolen property was necessarily material since it demonstrates a specific predisposition to dishonesty. (Pen. Code, § 496 [guilty knowledge is element of offense]; cf., People v. Spearman (1979) 25 Cal.3d 107, 114 [ 157 Cal.Rptr. 883, 599 P.2d 74].) We disagree. As we have said, the magistrate must assume, subject to rebuttal in the affidavit, that a police informant may be unreliable. Thus, evidence of general dishonesty which might be admissible at trial to impeach an otherwise convincing witness is not necessarily important to the fair portrayal of an undercover informant's reliability in a warrant affidavit.

(14) We caution that when the affiant knows or should know of specific facts which bear adversely on the informant's probable accuracy in the particular case, those facts must be disclosed. For example, if police have actually threatened or coerced the informant, or the informant bears a grudge against the defendant or is seeking to avoid or mitigate personal difficulties with the authorities, concrete evidence on those issues is material for purposes of the affidavit. In addition, if the informant's statements are substantially contradicted by independent police investigation, or if the affiant knows or should know of other specific circumstances which do or should lead him to suspect the informant's current credibility, the affidavit must say so.

(15) Similarly when the affidavit makes specific affirmative disclosures for purposes of buttressing the informer's general reliability, it must also include the equally specific adverse information necessary to prevent misrepresentation. (16) (See fn. 12.) For example, if the affidavit states that the informant has proved reliable in previous investigation it must also set forth similar instances of prior unreliability. (See Moylan, supra, 25 Mercer L.Rev. at p. 759.) (13b) As we have explained, the suppression hearing in this case revealed no specific indicia of inaccuracy; and the affidavit set forth general facts sufficient to invoke the suspicion and scrutiny appropriate for police informants generally. Thus the record fails to show that material facts bearing on informant's credibility and reliability were omitted from the affidavit.

Conclusion

Because we think that the affidavit was not substantially misleading, the warrant must stand unless Officer Matt acted recklessly or with intent to deceive when he omitted the facts at issue.

The order suppressing evidence and the judgment of dismissal are reversed. The cause is remanded for further hearings solely on the issue whether facts were excluded from the affidavit recklessly or with the specific intent of misleading the magistrate.

Tobriner, J., Mosk, J., Richardson, J., and Manuel, J., concurred.