We now consider the application of the collateral estoppel doctrine to successive criminal prosecutions. George Brackett appeals the denial of his motion to dismiss his indictment, arguing that the Double Jeopardy Clause bars the instant prosecution for conspiracy to possess with intent to distribute marihuana in violation of 21 U.S.C. § 846(a)(1). The government cross-appeals, arguing that the district court erred in suppressing evidence introduced in a previous prosecution for possession with intent to distribute marihuana. We affirm on the appeal, reverse on the cross-appeal, and remand.
I.
On September 18, 1992, Brackett was stopped at a border patrol checkpoint in Falfurrias, Texas, and consented to a search of his tractor-trailer truck. Border patrol officers discovered 247 kilograms of marihuana in the truck, and Brackett was arrested.
Brackett was indicted on one count of possession with intent to distribute marihuana in violation of 21 U.S.C. § 841(a)(1). At trial, he did not contest the fact that he had been in possession when he was arrested; instead, he pleaded ignorance, claiming that he had no knowledge of the marihuana and speculating that the drugs must have been placed in the truck, without his knowledge, while it was unattended. Accordingly, the prosecution and the defense both acknowledged that mens rea was the only disputed issue for the jury. Brackett was acquitted.
Subsequently, the government discovered evidence implicating Brackett as a drug courier in a marihuana distribution conspiracy. Consequently, he was indicted on one count *1398 of conspiracy to possess with intent to distribute marihuana in violation of 21 U.S.C. §§ 846(a)(1) and 841(b)(1)(B). The conspiracy alleged in the indictment occurred from April 1990 to May 1994, including the events charged in the prior possession prosecution. Moreover, three alleged co-conspirators pleaded guilty to charges of possession with intent to distribute, implicating Brackett in the conspiracy and offering testimony about the September 18, 1992, marihuana shipment to substantiate their allegations.
Brackett filed a pretrial motion to dismiss the indictment, claiming that it constituted a successive prosecution barred by the Double Jeopardy Clause, insofar as he had been acquitted previously of the substantive offense of possession with intent to distribute. The district court denied the motion but ordered the suppression of all evidence introduced in the prior possession prosecution, concluding that collateral estoppel barred the government’s use of that evidence to prove any fact necessarily decided by the jury in acquitting Brackett of the possession offense.
Brackett appeals the denial of his pretrial motion to dismiss the indictment, which is an appealable order under the collateral order doctrine.
See Abney v. United States,
II.
The doctrine of collateral estoppel is incorporated into the Double Jeopardy Clause.
Ashe v. Swenson,
This court has consistently held that collateral estoppel may affect successive criminal prosecutions in one of two ways. First, it will completely bar a subsequent prosecution if one of the facts necessarily determined in the former trial is an essential element of the subsequent prosecution. Second, while the subsequent prosecution may proceed, collateral estoppel will bar the introduction or argumentation of facts necessarily decided in the prior proceeding.
E.g., United States v. Deerman,
In this appeal, both applications of collateral estoppel are at issue: The district court declined to dismiss the indictment, but suppressed all evidence introduced in the prior possession prosecution. The application of collateral estoppel is a question of law that we review
de novo. United States v. Smith,
A.
It is axiomatic that “[cjollateral estoppel bars relitigation only of those facts necessarily determined in the first trial.”
Deerman,
This threshold determination is the touchstone of collateral estoppel doctrine. “When a ‘fact is not necessarily determined in a former trial, the possibility that it may have been does not prevent re-examination of that issue.’ ”
Lee,
Therefore, to determine which facts were “necessarily decided” in the first trial, following an acquittal by a general verdict, we examine the record of the prior proceeding, taking into account the pleadings, evidence, charge, and other relevant matter, in order to determine “ Vhether a rational jury could have grounded its verdict upon an issue other than that which the defendant seeks to foreclose from consideration.’”
Ashe,
Following this directive, we have taken a functional approach to collateral estoppel in criminal cases, like the instant appeal, in which a defendant was first acquitted by a general verdict and later invoked collateral estoppel to bar a subsequent prosecution.
See, e.g., Deerman,
It is not difficult to discern the facts “necessarily decided” by the jury in the first trial. Brackett did not deny that he was in possession of 247 kilograms of marihuana when arrested, nor did he contest the physical evidence and eyewitness testimony. To the contrary, he freely conceded all the facts relevant to the actus reus and staked his defense exclusively on the question of mens rea.
Insisting that he had no knowledge of the marihuana, Brackett characterized himself as an innocent driver who had been used as an unwitting drug courier by drug smugglers, and the jury apparently believed him. Under these circumstances, there is only one rational explanation for the general verdict of acquittal: The government did not prove, beyond a reasonable doubt, that Brackett knew of the 247 kilograms of marihuana in his truck on September 18,1992. Accordingly, the jury “necessarily decided” only that Brackett did not knowingly possess marihuana with intent to distribute on that date. 4
Having determined which facts were “necessarily decided” in the first trial, we must decide whether the government is attempting to relitigate the same facts in the conspiracy trial.
See Levy,
B.
Collateral estoppel completely bars a subsequent prosecution only when a fact “necessarily determined” in the first prosecution is an essential element of the offense charged in the subsequent prosecution.
See Kalish,
In order to prove the existence of a conspiracy to possess with intent to distribute marihuana, the government is required to prove three essential elements beyond a reasonable doubt: first, that an agreement existed to violate the federal narcotics laws; second, that the defendant knew of the existence of the agreement; and third, that he voluntarily participated in the conspiracy.
See United States v. Garcia,
*1400
As we have stated, the jury “necessarily determined” only that the government had failed to prove, beyond a reasonable doubt, that Brackett knew of the marihuana discovered in his truck on September 18, 1992. To convict Brackett for conspiracy, however, the government need not prove that he knew of the marihuana confiscated at the checkpoint; to the contrary, the government is required to prove only that Brackett knew of an agreement to violate the federal narcotics laws and voluntarily participated in that agreement.
See, e.g., Garcia,
Under these circumstances, Brackett’s acquittal of possession with intent to distribute does not collaterally estop the United States from prosecuting him, in a subsequent proceeding, for conspiracy to possess with intent to distribute. Accordingly, the district court did not err in refusing to dismiss the indictment. 6
C.
Even when a subsequent prosecution is not completely barred, this court has held that collateral estoppel may bar the admission or argumentation of
facts necessarily
decided in the first trial.
See, e.g., Deerman,
A general verdict of acquittal, exculpating the defendant of liability for a substantive offense, does not estop the government from introducing the same evidence in a subsequent prosecution for conspiracy to commit the same offense.
E.g., United States v. Garza,
Accordingly, the government may introduce evidence of an alleged criminal act, notwithstanding the fact that the defendant previously has been acquitted of the substantive offense, to prove participation in a conspiracy to commit the substantive offense. Overt acts in furtherance of a conspiracy need not be criminal; therefore, acquittal for the substantive offense does not bar the admission of the same evidence in a subsequent conspiracy trial. “Merely because appellants were acquitted of the substantive ... charges does not mean that the facts upon which the charges were based cannot later be used as non-criminal overt acts in furtherance of the conspiracy to commit the substantive offenses.” Id. at 1209-10. 7
The Supreme Court has placed its imprimatur on this principle. In
Dowling v. United States,
When the same evidence is admissible for a purpose that does not require proof beyond a reasonable doubt, therefore, collateral estoppel does not bar the government from relitigating the issue in a subsequent proceeding.
Id.
at 348-49,
Although the jury in the first trial “necessarily determined” that the government had failed to prove, beyond a reasonable doubt, that Brackett knew of the 247 kilograms of marihuana in his truck, the government need not prove that fact beyond a reasonable doubt in the conspiracy prosecution, as it is not an ultimate issue. In order to convict Brackett for participation in the conspiracy, the government must prove only that Brackett knowingly participated in a conspiracy to violate the federal narcotics laws; evidence concerning the September 18, 1992, marihuana shipment is relevant to establish Brackett’s voluntary participation in the conspiracy, but is not required to prove the essential elements of the offense. Accordingly, collateral estoppel does not bar the government from relitigating evidence originally offered in the possession trial, because the burden of proof governing the admissibility of evidence in the conspiracy prosecution is lower than the burden of proof required to establish an ultimate issue in the possession trial. 10
*1402-1412 The admissibility of evidence relevant to an ultimate issue is governed by Fed. R. Evid. 401, which defines “relevant evidence” as evidence “having any tendency to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would be without the evidence.” 11 It is indisputable that evidence concerning the September 18, 1992, marihuana shipment is highly relevant to the determination whether Brackett participated in a conspiracy to possess with intent to distribute marihuana, regardless of the fact that the evidence was insufficient to prove, beyond a reasonable doubt, his guilt of the substantive offense. Evidence that Brackett had transported 247 kilograms of marihuana, when corroborated by the statements of his alleged co-conspirators, would have a tendency to prove the essential elements of conspiracy to possess with intent to distribute marihuana: that an agreement existed to violate the narcotics laws, that Brackett knew of the agreement, and that he voluntarily participated in the conspiracy. Therefore, the evidence is relevant and admissible. 12
In the instant case, the standard governing the admissibility of evidence is lower than was the burden of proof in the first trial. Under both Fifth Circuit precedent and Dowling, therefore, the government is not collaterally estopped from introducing the same evidence in the conspiracy prosecution. Accordingly, the district court erred in suppressing all evidence introduced in the possession trial.
III.
The order refusing to dismiss the indictment is AFFIRMED. The suppression order is REVERSED, and this matter is REMANDED for further proceedings consistent with this opinion.
Notes
. Accord
United States v. Kalish,
.
See also Schiro v. Farley,
. Accord Deerman,
.
Cf. Ashe,
.
See Lee,
.
In the district court, Brackett also claimed the Double Jeopardy Clause bars the subsequent conspiracy prosecution. Insofar as he renews this claim on appeal, it is without merit. A substantive offense and conspiracy to commit that offense are not the "same offense” for purposes of double jeopardy.
United States v. Felix,
Likewise, Brackett suggests that a successive prosecution is barred if the government seeks to establish an essential element of the second offense by proving conduct for which the defendant was prosecuted in the first prosecution.
See Grady v. Corbin,
.See also United States v. Morris,
. The Court has recently reaffirmed this principle, holding that a general acquittal does not collaterally estop the government from introducing the same evidence in a subsequent proceeding governed by a lower burden of proof.
See United States v. Watts,
-U.S. --, -,
. In the aftermath of
Dowling,
collateral estoppel bars the introduction of evidence in a subsequent proceeding only if the facts "necessarily decided” in the first trial were determined under the same burden of proof applicable in the subsequent trial. Accordingly,
Dowling
calls into question the line of cases holding that collateral estoppel may bar the admission or argumentation of facts necessarily decided in the first trial, even if the subsequent prosecution is not completely barred.
See, e.g., Deerman,
Because only ultimate facts must be established beyond a reasonable doubt, however,
Dowling
effectively limits the doctrine of collateral estoppel to cases in which the government seeks to relitigate an essential element of the offense.
See Dowling,
Given the narrow interpretation of collateral estoppel endorsed in Dowling, it is difficult to conceive of a case in which collateral estoppel would bar the admission or argumentation of facts necessarily decided in the first trial, without completely barring the subsequent prosecution. In the instant case, however, we have no occasion to consider whether Dowling has overruled this line of decisions, and we leave that question for another day.
.Cf. Bourjaily v. United States,
. In Dowling, the contested evidence concerned extrinsic evidence of other bad acts, admissible under Fed. R. Evid. 404(b). In the instant case, however, the evidence is intrinsic evidence directly relevant to the conspiracy charge and thus is governed by Fed. R. Evid. 401-03.
. Relevant evidence is presumptively admissible. Fed. R. Evid. 402. Relevant evidence may be excluded by the district court if the probative value of the evidence is “substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury.” Fed. R. Evid. 403. Had the district court excluded all evidence introduced in the possession trial pursuant to rule 403, we would review that determination for abuse of discretion.
See, e.g., Morris,
