dissenting.
The Court today decides that a district court’s determinations whether there was probable cause to justify a warrant-less search and reasonable suspicion to make an investigatory stop should be reviewed de novo. We have in the past reviewed some mixed questions of law and fact on a de novo basis, and others on a deferential basis, depending upon essentially practical considerations. Because, with respect to the questions at issue here, the purpose of the determination and its extremely fact-bound nature will cause de novo review to have relatively little benefit, it is in my view unwise to require courts of appeals to undertake the searching inquiry that standard requires. I would affirm the judgment of the Court of Appeals.
As the Court recognizes, determinations of probable cause and reasonable suspicion involve a two-step process. First, *701a court must identify all of the relevant historical facts known to the officer at the time of the stop or search; and second, it must decide whether, under a standard of objective reasonableness, those facts would give rise to a reasonable suspicion justifying a stop or probable cause to search. See ante, at 696-697. Because this second step requires application of an objective legal standard to the facts, it is properly characterized as a mixed question of law and fact. See ibid,.; Pullman-Standard v. Swint, 456 U. S. 273, 289, n. 19 (1982).
Merely labeling the issues “mixed questions,” however, does not establish that they receive de novo review. While it is well settled that appellate courts “accep[t] findings of fact that are not ‘clearly erroneous’ but decidje] questions of law de novo,” First Options of Chicago, Inc. v. Kaplan, 514 U. S. 938, 948 (1995), there is no rigid rule with respect to mixed questions. We have said that “deferential review of mixed questions of law and fact is warranted when it appears that the district court is ‘better positioned’ than the appellate court to decide the issue in question or that probing appellate scrutiny will not contribute to the clarity of legal doctrine.” Salve Regina College v. Russell, 499 U. S. 225, 233 (1991) (citing Miller v. Fenton, 474 U. S. 104, 114 (1985)).
These primary factors that counsel in favor of deferential review of some mixed questions of law and fact — expertise of the district court and lack of law-clarifying value in the appellate decision — are ordinarily present with respect to determinations of reasonable suspicion and probable cause. The factual details bearing upon those determinations are often numerous and (even when supported by uncontro-verted police testimony) subject to credibility determinations. An appellate court never has the benefit of the district court’s intimate familiarity with the details of the case — nor the full benefit of its hearing of the live testimony, unless the district court makes specific findings on the “totality of the circumstances” bearing upon the stop or search. *702As we recognized in Cooter & Gell v. Hartmarx Corp., 496 U. S. 384 (1990), a case holding that deferential (abuse-of-discretion) review should be applied to a district court’s Federal Rule of Civil Procedure 11 determination that an attorney did not conduct a reasonable inquiry or entertain a “substantiated belief” regarding the nonfrivolousness of the complaint, see id., at 393: A district court, “[fjamiliar with the issues and litigants ... is better situated than the court of appeals to marshal the pertinent facts and apply the fact-dependent legal standard . . . .” Id., at 402.
Moreover, as the Court acknowledges, “reasonable suspicion” and “probable cause” are “commonsense, nontechnical conceptions that deal with ‘ “the factual and practical considerations of everyday life on which reasonable and prudent men, not legal technicians, act.””’ Ante, at 695 (quoting Illinois v. Gates, 462 U. S. 213, 231 (1983) (quoting Brinegar v. United States, 338 U. S. 160, 175 (1949))). Where a trial court makes such commonsense determinations based on the totality, of circumstances, it is ordinarily accorded deference. What we said in a case concerning the question whether certain payments were a “gift” excludable from income under the Internal Revenue Code is equally pertinent here.
“Decision of the issue presented in these cases must be based ultimately on the application of the fact-finding tribunal’s experience with the mainsprings of human conduct to the totality of the facts of each case. The nontechnical nature of the . . . standard, the close relationship of it to the data of practical human experience, and the multiplicity of relevant factual elements, with their various combinations, creating the necessity of ascribing the proper force to each, confirm us in our conclusion that primary weight in this area must be given to the conclusions of the trier of fact.” Commissioner v. Duberstein, 363 U. S. 278, 289 (1960).
*703With respect to the second factor counseling in favor of deferential review, level of law-clarifying value in the appellate decision: Law clarification requires generalization, and some issues lend themselves to generalization much more than others. Thus, in Pierce v. Underwood, 487 U. S. 552, 562 (1988), a principal basis for our applying an abuse-of-discretion standard to a district court’s determination that the United States’ litigating position was “substantially justified” within the meaning of the Equal Access to Justice Act, 28 U. S. C. § 2412(d), was that the question was “a multifarious and novel question, little susceptible, for the time being at least, of useful generalization.” 487 U. S., at 562. Probable-cause and reasonable-suspicion determinations are similarly resistant to generalization; As the Court recognizes, these are “fluid concepts,” “ ‘not readily, or even usefully, reduced to a neat set of legal rules’ and “because the mosaic which is analyzed for a reasonable-suspicion or probable-cause inquiry is multifaceted, ‘one determination will seldom be a useful “precedent” for another.’ ” Ante, at 695-696, 698 (quoting Illinois v. Gates, supra, at 232, 238, n. 11). The Court maintains that there will be exceptions to this — that fact patterns will occasionally repeat themselves, so that a prior de novo appellate decision will provide useful guidance in a similar case. Ante, at 698. I do not dispute that, but I do not understand why we should allow the exception to frame the rule. Here, as in Anderson v. Bessemer City, 470 U. S. 564, 574-575 (1985), “[duplication of the trial judge’s efforts in the court of appeals would very likely contribute only negligibly to the accuracy of fact determination at a huge cost in diversion of judicial resources.”
The facts of this very case illustrate the futility of attempting to craft useful precedent from the fact-intensive review demanded by determinations of probable cause and reasonable suspicion. On remand, in conducting de novo review, the Seventh Circuit might consider, inter alia, the following *704factors relevant to its determination whether there was probable cause to conduct a warrantless search and reasonable suspicion justifying the investigatory stop: (i) the two NADDIS tips; (ii) that the car was a 1981 two-door General Motors product; (iii) that the car was from California, a source State; (iv) that the car was in Milwaukee; (v) that it was December; (vi) that one suspect checked into the hotel at 4 a.m.; (vii) that he did not have reservations; (viii) that he had one traveling companion; (ix) that one suspect appeared calm but shaking; and (x) that there was a loose panel in the car door. If the Seventh Circuit were to find that this unique confluence of factors supported probable cause and reasonable suspicion, the absence of any one of these factors in the next case would render the precedent inapplicable.
Of course, even when all of the factors are replicated, use of a de novo standard as opposed to a deferential standard will provide greater clarity only where the latter would not suffice to set the trial court’s conclusion aside. For where the appellate court holds, on the basis of deferential review, that it was reversible error for a district court to find probable cause or reasonable suspicion in light of certain facts, it advances the clarity of the law just as much as if it had reversed the district court after conducting plenary review.
In the present case, an additional factor counseling against de novo review must be mentioned: The prime benefit of de novo appellate review in criminal cases is, of course, to prevent a miscarriage of justice that might result from permitting the verdict of guilty to rest upon the legal determinations of a single judge. But the issue in these probable-cause and reasonable-suspicion cases is not innocence but deterrence of unlawful police conduct. That deterrence will not be at all lessened if the trial judge’s determination, right or wrong, is subjected to only deferential review.
The Court is wrong in its assertion, ante, at 698-699, that unless there is a dual standard of review — deferential review of a magistrate’s decision to issue a warrant, and de novo *705review of a district court’s ex post facto approval of a war-rantless search — the incentive to obtain a warrant would be eliminated. In United States v. Leon, 468 U. S. 897, 913 (1984), we held that “reliable physical evidence seized by officers reasonably relying on a warrant issued by a detached and neutral magistrate ... should be admissible in the prosecutor’s case in chief.” Only a warrant can provide this assurance that the fruits of even a technically improper search will be admissible. Law enforcement officers would still have ample incentive to proceed by warrant.
Finally, I must observe that the Court does not appear to have the courage of its conclusions. In an apparent effort to reduce the unproductive burden today’s decision imposes upon appellate courts, or perhaps to salvage some of the trial court’s superior familiarity with the facts that it has cast aside, the Court suggests that an appellate court should give “due weight” to a trial court’s finding that an officer’s inference of wrongdoing (i. e., his assessment of probable 2ause to search) was reasonable. Ante, at 700. The Court cannot have it both ways. This finding of “reasonableness” is precisely what it has told us the appellate court must review de novo; and in de novo review, the “weight due” to a trial court’s finding is zero. In the last analysis, therefore, the Court’s opinion seems to me not only wrong but contradictory.
* * *
I would affirm the judgment of the Seventh Circuit on the ground that it correctly applied a deferential standard of review to the District Court’s findings of probable cause and reasonable suspicion.