Here's the conclusion:
While it is possible, perhaps even probable, that Espinoza-Valdez was on the mountaintop to act as a scout for drug traffickers, a reasonable suspicion or probability of guilt is not enough. Guilt, according to the basic principles of our jurisprudence, must be established beyond a reasonable doubt. Here, it was not: Viewing the entirety of the evidence in the light most favorable to the government, there was insufficient evidence upon which a reasonable mind might fairly find the existence of a conspiracy to import or distribute marijuana — or of Espinoza-Valdez’s agreement to join such a conspiracy — beyond a reasonable doubt.The majority explained the government could not rely almost entirely on drug-courier profile evidence: "A drug expert’s testimony cannot substitute for witnesses who actually observed or participated in the illegal activity. Nor can it be permitted to so submerge the factual evidence that its unfair prejudicial effect substantially outweighs any probative value it might have."
