dissenting.
¶ 33 I cannot join the court’s opinion for two separate and independent reasons. First, I agree with the United States Court of Appeals for the Seventh Circuit that there is no per se bar to the admission of drug courier profile evidence as substantive proof of guilt. United States v. Foster, 939 F.2d 445, 451 (7th Cir.1991). Second, even if such *549evidence were inadmissible, this is a plain case of harmless error.
I. Drug Courier Profile as Substantive Evidence of Guilt2
¶34 There is a split of authority over whether drug courier profile evidence is admissible on the question of guilt. The differences are best expressed in two competing opinions in the United States Court of Appeals. In United States v. Lui, 941 F.2d 844, 847 (9th Cir.1991), the court rejected the use of drug courier profile evidence as substantive evidence of guilt, believing it to be inherently prejudicial. But in United States v. Foster, 939 F.2d at 451-52, the court rejected any per se bar to the admission of drug courier profile evidence, leaving the question of potential prejudice in any given case to the trial court. I prefer the Foster approach because I believe that the question of admissibility in the first instance is a question of relevance, not a question of prejudice. As the court said, “[i]f the testimony is relevant to the defendant’s guilt or innocence, then it is potentially admissible at trial.” Id. at 451. Evidence is relevant if it has “any tendency” to make the existence of any material fact more or less probable than it would be without the evidence. Rule 401, Ariz. R. Evid. All relevant evidence is admissible unless otherwise provided. Rule 402, Ariz. R. Evid.
¶35 Drug courier profile evidence does indeed meet the threshold “tendency” test of Rule 401. Through experience and training in the culture and practices of the drug trade, one can help the juiy unmask otherwise neutral behavior. The expert’s testimony is relevant to the issue of knowledge — it has a “tendency” to make it more probable that the defendant knew the suitcase contained drugs. For example, in Foster, the court said it “may be innocent behavior to purchase a one-way train ticket, for cash, on the same day as departure from a source city for illegal drugs, under a false name, and carrying a beeper, but it is a fair use of expert testimony to offer another explanation for such behavior.” 939 F.2d at 452.
If 36 Prejudice, on the other hand, is squarely addressed in Rule 403, Ariz. R. Evid., where evidence otherwise relevant may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice. Judgment calls under Rule 403 have nothing to do with general admissibility under Rule 401. By adopting a per se rule of exclusion, the court melds the two doctrines into one. Relevant evidence will now be excluded in some cases in which it ought to be admitted. I agree with the Seventh Circuit that drug courier profile evidence is helpful to the jury because
[djespite our country’s “war on drugs’ and its accompanying media coverage, it is still a reasonable assumption that jurors are not well versed in the behavior of drug dealers. ‘The investigator and the expert witness both serve as a link to the drug culture in providing the jury with [an] understanding of the intricate patterns and modus operandi ’ of those involved in narcotics trafficking.
939 F.2d at 451-52 (citation omitted).
II. Harmless Error3
¶ 37 The majority prefers the per se exclusionary approach of the Ninth Circuit. But in United States v. Lui, supra, the Ninth Circuit found that the admission of such evidence was harmless where the record overwhelmingly demonstrated the defendant’s guilt. There, Lui was carrying nearly 28 pounds of heroin in suitcases to which he had the keys and he otherwise acted suspiciously. 941 F.2d at 848. Here, the suitcase contained a significant amount of drugs that were professionally packaged in heat-sealed plastic bags. Lee surrendered the suitcase at the check-in counter and had the keys to their locks. These facts alone provide overwhelming evidence of guilt. Under these *550circumstances, the majority could say with safety that what it perceives to be error was harmless indeed.
¶ 38 I therefore respectfully dissent.
. Although the majority adopts a per se rule of exclusion of drug courier profile evidence as substantive proof of guilt, it acknowledges that such evidence may be admissible for other purposes, e.g., to establish probable cause. Ante, at ¶11.
. Under the majority’s per se approach, the admission of drug courier profile evidence as substantive proof of guilt will always be error. But even under the majority’s approach, it will not always be reversible error. Its erroneous admission is subject to a harmless error analysis.