dissenting:
I dissent because the district court correctly found that the government agents lacked probable cause to arrest the defendant.
“Probable cause for a warrantless arrest exists if ‘under the totality of the facts and circumstances known to the arresting officer, a prudent person would have concluded that there was a fair probability that the *286suspect had committed a crime.’ ” United States v. Fixen, 780 F.2d 1434, 1436 (9th Cir.1986) (quoting United States v. Gonzales, 749 F.2d 1329, 1337 (9th Cir.1984)). Evidence obtained from an unlawful arrest is suppressed as fruit of the poisonous tree. Wong Sun v. United States, 371 U.S. 471, 487-88, 83 S.Ct. 407, 417, 9 L.Ed.2d 441 (1963).
I agree with the district court and the case officer in charge of the investigation here that the government agents lacked probable cause to arrest the defendant when they stopped the 1983 Ford. At that time, the only information the officers had about the defendant was that he (1) accompanied Dorris when he bought chemicals and five gallons of distilled water; (2) purchased four large trash cans and other household items from a drugstore; and (3) was a passenger in the Ford when the agents stopped it. These facts are clearly insufficient to establish probable cause that the defendant had committed or was committing a crime.
Unlike the majority, I believe that United States v. Hillison, 733 F.2d 692 (9th Cir.1984), requires that we affirm the district court. In that case, government agents observed two individuals acting nervously in the San Diego International Airport. The agents followed the individuals and observed them purchasing paper items. The next day, the two individuals mailed a package, which the agents segregated from the normal mail. When the two individuals vacated their motel room, the agents searched it and found wrapping paper and marijuana seeds. A narcotics detector dog then sniffed and alerted the agents to the package that the individuals had mailed. The agents obtained a search warrant for the package and discovered that it contained a large quantity of cocaine.
In Hillison, we held that buying supplies and acting nervously did not establish probable cause. Id. at 695. The agents acquired probable cause only after the dog alerted them to drugs in the package. Id. at 696. At that point the agents knew that the suspects were committing a crime.
We also held in Hillison that under those facts the agents obtained probable cause to arrest a third individual whom they observed driving the two suspects around and spending considerable time with them. In so holding, we reaffirmed the well-established principle that mere association, even with persons known to be committing a crime, is insufficient to establish probable cause:
In order to find probable cause based on association with persons engaging in criminal activity, some additional circumstances from which it is reasonable to infer participation in criminal enterprise must be shown____ One important consideration in assessing the significance of the association is whether the known criminal activity was contemporaneous with the association____ Another is whether the nature of the criminal activity is such that it could not normally be carried on without the knowledge of all persons present____ [T]he mere propinquity with known criminals does not, without more, give rise to probable cause.
Id. at 697 (citations omitted); see also United States v. Epperson, 485 F.2d 514, 515 (9th Cir.1973). Hillison established three requirements to infer participation from association. First, the association must rise to a sufficient level of contact with the individuals. 733 F.2d at 697 (“prolonged contact” between the individuals). Second, the third person’s extensive association with the individuals must have occurred while they engaged in known criminal activity. Id. Third, the court found that the criminal activity there was the type “normally carried on with [ ] the knowledge of all persons present.” Id. Moreover, the Hillison court noted that the third individual engaged in suspicious activity, such as renting a car under an alias and lying to officers when questioned. Id. at 697-98.
None of these three requirements are met here. First, the defendant’s only asso*287ciation in this case was riding in a car subject to a search warrant with three individuals whose identity the government agents did not know; purchasing innocent household items; and accompanying Dorris to a chemical company and a grocery store. This tenuous association falls far below the level of involved contact required by Hillison. Second, the limited evidence in the record does not support any inference that police knew that anyone with whom the defendant was associating had committed a crime. Third, and most important, the criminal activities involved here — attempted manufacture and conspiracy to manufacture — may be “carried on without the knowledge of all persons present.” Id. at 697. A reasonable person would not necessarily have been suspicious of the purchase of household items, and the record does not suggest that any readily recognizable drugs were ever produced.
The majority asserts that it “taxes credulity” to believe that Moses would not have been suspicious of illegal activity in light of the purchases of chemicals and “abnormally large quantities and odd combinations of household items.” Majority op. at 285. Yet, the key distinction between Hillison and the present case is that in Hillison the individual should have been aware of criminal activity because the items involved— marijuana and a large quantity of cocaine — were contraband and clearly illegal. As far as I know, no law prohibits the purchases of chemicals or trash cans — even in abnormally large quantities and odd combinations, whatever those terms may mean.
The district court’s finding of no probable cause is further buttressed by the testimony of Officer Mclntyire, the case officer supervising the investigation, that she believed probable cause did not exist to arrest the defendant prior to discovering the PCC in the trunk. This court has maintained that the subjective impressions of arresting officers are immaterial to our determination of probable cause. See United States v. Fixen, 780 F.2d 1434, 1436 n. 1 (9th Cir.1986). However, the statement in this case that the officer believed probable cause did not exist — rather than being a self-serving statement, which might be somewhat suspect — is more akin to a declaration against interest, and we should consider such a statement in our determination.
The majority is apparently willing to accept the officer’s statement that she thought the agents had probable cause to obtain a warrant to search Moses. Majority op. at 285. But the majority is unwilling to credit the same officer’s testimony that she did not believe there was probable cause to arrest Moses. This paradoxical position is even more perplexing given the majority’s acceptance of police officers’ expertise in evaluating suspicious conduct: “ ‘it is important to recall that a trained law enforcement agent may be able to perceive and articulate meaning in a given conduct which would be wholly innocent to the untrained observer.’ ” Id. at 284 (quoting United States v. Mendenhall, 446 U.S. 544, 563, 100 S.Ct. 1870, 1882, 64 L.Ed.2d 497 (1980) (Powell, J., concurring)).
Moreover, the majority’s reliance on Florida v. Royer, 460 U.S. 491, 507, 103 S.Ct. 1319, 1329, 75 L.Ed.2d 229 (1983), is misplaced. Although the plurality opinion in that case examined whether probable cause existed, the Court agreed with the officer’s opinion that probable cause was lacking. Thus, the Court did not define how much weight to accord the officer’s opinion or explain when a court should disregard an officer’s opinion that probable cause was absent. Of course, there are some circumstances when a police officer’s opinion that probable cause is absent should not be credited — for example, when the officer has an erroneous view of the law. However, such circumstances are not present here. The majority gives no reason why the “trained” opinion of the officer — that the seemingly innocent activity did not constitute probable cause — was mistaken.
I believe that the district court correctly concluded that the government agents lacked probable cause to arrest the defend*288ant when they stopped the Ford, and I would affirm.