Opinion by Judge GRABER; Concurrence by Judge KLEINFELD.
OPINION
GRABER, Circuit Judge:
A jury convicted Defendant Steven Gene Chase of violating 18 U.S.C. § 115(a)(1)(B) after he made a threat against agents of the Federal Bureau of Investigation. The jury acquitted him of a charge involving threats to other FBI agents. The threat underlying Defendant’s conviction was expressed to a telephone operator at a Kaiser Permanente clinic. The threats as to which Defendant was acquitted were communicated, during therapeutic sessions, to his psychiatrist, who testified about them.
On appeal, Defendant argues that the psychotherapist-patient privilege precluded the psychiatrist’s testimony about what he told her during therapeutic sessions. We agree and hold that the privilege applied; we decline to craft a “dangerous patient” exception to the testimonial privilege. Thus, the district court erred in admitting the psychiatrist’s testimony regarding threats that Defendant had related during treatment. Nonetheless, we affirm Defendant’s conviction, because the error was harmless.
BACKGROUND
Defendant began receiving treatment at Kaiser Permanente from psychiatrist Kay Dieter in 1997. He was suffering from irritability, depression, and symptoms of anger. Defendant experienced, among other things, episodes of rage and obsessive rumination against certain people, including those who participated in various legal proceedings in which Defendant was involved. Eventually Defendant was diagnosed with bipolar type II disorder. He received disability benefits due to his psychiatric condition. Defendant met with Dr. Dieter every couple of months for therapy and for management of his medication. Defendant met more often (ranging from bi-weekly to monthly) with psychologist Robert Schiff for psychotherapy.
During a counseling session on August 18, 1999, Defendant showed Dr. Dieter his day planner, which contained a list of names, addresses, and social security numbers. The list included two FBI agents who had investigated complaints lodged by Defendant. Defendant confided to Dr. Dieter that he had thought about injuring or killing these people and that he had threatened some of the listed individuals several times during the preceding five years.
Dr. Dieter became concerned that Defendant might act on his threats. Defendant told Dr. Dieter that he had no intention to act immediately on his homicidal thoughts. Nonetheless, Dr. Dieter warned Defendant that if he told her specifics about whom he planned to kill, she would have a duty to disclose the threats to the intended victims so that they could protect themselves.
Following this session, Dr. Dieter discussed with one of her supervisors her concerns regarding Defendant’s threats. She asked whether she had a duty to warn potential victims. The supervisor suggested that Dr. Dieter try to elicit more information from Defendant before taking any further action.
On October 18, 1999, Defendant called Dr. Dieter to tell her that he had argued [980]*980with his wife and was extremely upset. Defendant told Dr. Dieter that he had a life insurance policy that would pay off if anything should happen to him. Fearing that Defendant was losing his support system, Dr. Dieter met with a supervisor and with Kaiser Permanente’s legal counsel to discuss again whether Defendant’s threats should be disclosed. Legal counsel advised Dr. Dieter to contact the local police department in Corvallis, Oregon, Defendant’s home town. Dr. Dieter contacted the Corvallis police on October 19. On October 25, agents of the FBI got in touch with her. She disclosed to the FBI agents the threatening statements that Defendant had made during therapeutic sessions and identified the people whom Defendant had threatened. Dr. Dieter’s supervisors instructed her to continue to cooperate with the authorities and to attempt to elicit more information about Defendant’s plans during their next appointment.
Defendant and Dr. Dieter met again on October 27. Dr. Dieter did not tell Defendant about her disclosures to the authorities or her instructions from her supervisors. Defendant related the details of another fight with his wife and told Dr. Dieter that his mother had just been diagnosed with cancer. Defendant reiterated his frustration with the legal system (including the FBI, which Defendant complained was not protecting him adequately) and said that, if a lien against his house was not dropped by the time he met with his lawyer on November 2, “he would get his guns, get in his vehicle and have himself some justice.” Defendant told Dr. Dieter that he had gathered more information on the people he intended to kill and that he had located all but four of those on his list. Dr. Dieter repeated her admonition regarding her duty to warn Defendant’s intended victims. Defendant alternated between claiming that he did not have any plans to act immediately and reiterating his threats.
On October 28, FBI Agent Donald McMullen spoke with Dr. Dieter and told her that the FBI was planning to interview Defendant and to execute a search warrant on his home, looking for weapons and the day planner containing the list of threatened individuals. Later that day, Defendant left several voice-mail messages for Dr. Dieter, telling her that he believed he was about to be arrested. (Apparently a neighbor of Defendant’s, who was curious about why United States Marshals were questioning her about Defendant and speaking of arresting him, had called Defendant.) Defendant also spoke with two of the clinic’s telephone operators, telling one that “there are FBI Marshals that are on their way out to get me and if that happens, people are going to die.” Dr. Dieter did not return Defendant’s calls. Instead, she notified Agent McMullen to alert him to the fact that Defendant knew that the authorities were on their way.
Agent McMullen and his team went to Defendant’s home but, before proceeding, called for backup. Defendant’s wife arrived while the agents were waiting. The agents prevented her from entering the house. A series of cell-phone negotiations ensued, involving Defendant, his wife, and his lawyer. Finally, a deal was struck whereby Defendant would put his gun on a table and leave the house. As agreed, Defendant walked into his yard, assisted McMullen over a wall, and allowed himself to be handcuffed. Defendant told McMul-len about the gun on the table and about the location of the day planner; Defendant did not mention two other firearms that were hidden in the house. Defendant said that when he told the clinic operator that people were going to die if the agents came to his home, he meant that he would die. Defendant also referred to the threatening statements conveyed to Dr. Dieter as “hypothetical.”
[981]*981Defendant was arrested and charged on three counts: Count I (threatening to murder federal law enforcement officers who were preparing to execute a search warrant on his home); Count II (threatening to murder the FBI agents who, he complained, had failed to investigate his earlier complaints properly); and Count III (possession of firearms by a person adjudicated by the Social Security Administration to be mentally defective). The district court dismissed Count III before trial.
At trial, Defendant challenged the admissibility of (1) Dr. Dieter’s testimony relating to statements that Defendant had made during therapeutic sessions and (2) evidence of threats that he had made against individuals other than federal law enforcement officers. The district court held that Dr. Dieter’s testimony was admissible. The court reasoned that the federal psychotherapist-patient privilege did not apply because Dr. Dieter properly had determined that Defendant’s threats were serious when uttered, that harm was imminent, and that disclosure to authorities was the only means of averting the threatened harm. The district court also held that evidence of other threats was admissible under Federal Rule of Evidence 404(b). The court determined that this evidence was relevant under Count II to Defendant’s intent to retaliate against FBI agents for their perceived failure to investigate appropriately the people against whom Defendant had filed complaints.
Dr. Dieter testified at trial. She recounted the therapeutic sessions in which Defendant had threatened FBI agents and others (the basis of Count II). Two Kaiser Permanente telephone operators testified to the conversations they had with Defendant while federal agents were en route to his home (the basis of Count I).
Following the trial, the jury convicted Defendant on Count I (threatening the agents who were en route to execute the search warrant) but acquitted him on Count II (the threats communicated during sessions with Dr. Dieter). Defendant timely appealed his conviction, arguing that admission of Dr. Dieter’s testimony violated the psychotherapist-patient privilege and that other-acts evidence was improperly admitted under Rule 404(b). A three-judge panel of this court affirmed the district court’s evidentiary rulings and affirmed the conviction. United States v. Chase, 301 F.3d 1019 (9th Cir.2002) (per curiam). We then agreed to rehear this case en banc. 314 F.3d 1031 (9th Cir.2002).
STANDARD OF REVIEW '
We review de novo the ruling of a district court on the scope of a privilege. Oleszko v. State Comp. Ins. Fund, 243 F.3d 1154, 1156 (9th Cir.), cert. denied, 534 U.S. 892, 122 S.Ct. 208, 151 L.Ed.2d 148 (2001).
DISCUSSION
To answer the ultimate question whether Dr. Dieter’s testimony was properly admitted and, if not, whether Defendant is entitled to a reversal of his conviction, we will answer a series of four subsidiary questions:
• Was Defendant’s communication to Dr. Dieter of threats to third parties a confidential communication that, ordinarily, is subject to a federal testimonial privilege? We answer that question “yes.”
• Did Dr. Dieter properly disclose the threats to law enforcement personnel? Again, our answer is “yes.”
• Did Dr. Dieter’s disclosure destroy the federal testimonial privilege? Our answer is “no.” We hold that there is no dangerous-patient exception to the federal psychotherapist-patient testimonial privilege.
[982]*982• Does the district court’s error in allowing Dr. Dieter to testify- about what occurred during therapeutic sessions require us to reverse Defendant’s conviction? We answer “no” to this final question. Because the jury acquitted Defendant of the threats to which Dr. Dieter testified and because, on this record, the outcome on the count of conviction would have been the same without her testimony, we hold that the error was harmless.
A. Defendant’s communication to Dr. Dieter was confidential under state law and 'privileged under both state and federal law.
At the outset, we differentiate two distinct concepts: confidentiality and testimonial privilege. By “confidentiality,” we refer to the broad blanket of privacy that state laws place over the psychotherapist-patient relationship. By “privilege,” we mean the specific right of a patient to prevent the psychotherapist from testifying in court.
All 50 states and the District of Columbia have enacted laws protecting psychotherapist-patient confidentiality. See 3 Jack B. Weinstein & Margaret E. Berger, Weinstein’s Federal Evidence § 504.03[4][b], at p. 504-11 & n. 12 (2d ed.1997, Release No. 67-02/00) (listing statutes). These laws commonly perform two functions: They establish a testimonial privilege, and they also create a more general blanket of confidentiality to cover the relationship in all contexts. A psychiatrist who is subject to such a law may not testify in court as to therapeutic conversations with her patient; neither may she gossip about them with her grocer.
Oregon, where Defendant received treatment from Dr. Dieter, is no exception. Confidentiality is protected by statute. See, e.g., Or.Rev.Stat. § 677.190(5) (listing as a ground for revocation or suspension of a medical license the divulging of a patient’s confidences); 2003 Or. Laws ch. 86, § 1 (H.B.2305) (stating legislative policy to protect patients’ medical records from disclosure); Or.Rev.Stat. §§ 109.675-.695 (allowing minors 14 years of age or older to obtain diagnosis and treatment of, inter alia, a mental or emotional disorder, without parental knowledge or consent in most circumstances); Or.Rev.Stat. § 430.399(5) (providing that records of a drug- — or alcohol-treatment facility shall not be revealed without the patient’s consent); see also Humphers v. First Interstate Bank, 298 Or. 706, 696 P.2d 527 (1985) (explaining sources of confidentiality requirement). A concomitant state-court testimonial privilege is provided in Oregon Evidence Code § 504(2):
A patient has a privilege to refuse to disclose and to prevent any other person from disclosing confidential communications made for the purposes of diagnosis or treatment of the patient’s mental or emotional condition among the patient, the patient’s psychotherapist or persons who are participating in the diagnosis or treatment under the direction of the psychotherapist, including members of the patient’s family.
Defendant’s statements were made in the course and scope of treatment. Accordingly, Defendant’s communications to Dr. Dieter were confidential under state law (although an exception permitted disclosure of certain parts of the communications, as we explain below). That is so even though the threats that Defendant communicated arguably constituted a crime. Once Defendant finished uttering the threats, the charged crime was completed, and the psychiatrist was in the same position she would have occupied had her patient described a bank robbery in which he had participated a week earlier.1
[983]*983Defendant’s disclosures to his psychiatrist also were subject to a testimonial privilege in federal court, unless some exception applies. Federal Rule of Evidence Rule 501 states in part:
Except as otherwise required by the Constitution of the United States or provided by Act of Congress or in rules prescribed by the Supreme Court pursuant to statutory authority, the privilege of a witness, person, government, State, or political subdivision thereof shall be governed by the principles of the common law as they may be interpreted by the courts of the United States in the light of reason and experience.
“Reason and experience” are the “touchstones” for acceptance of a privilege under Rule 501. Jaffee v. Redmond, 51 F.3d 1346, 1355 (7th Cir.1995), aff'd, 518 U.S. 1, 116 S.Ct. 1923, 135 L.Ed.2d 337 (1996).
The Supreme Court, resolving a circuit split, first recognized a psychotherapist-patient privilege in Jaffee. There, the Court held that “confidential communications between a licensed psychotherapist and her patients in the course of diagnosis or treatment are protected from compelled disclosure under Rule 501 of the Federal Rules of Evidence.” Id. at 15, 116 S.Ct. 1923. In arriving at its conclusion, the Supreme Court acknowledged that testimonial privileges generally are disfavored, but observed that a testimonial privilege may be justified by a “public good transcending the normally predominant principle of utilizing all rational means for ascertaining truth.” Id. at 9 (internal quotation marks omitted).
The Jaffee Court paid particular attention to the experience of the states. The determination “[t]hat it is appropriate for the federal courts to recognize a psychotherapist privilege under Rule 501 is confirmed by the fact that all 50 States and the District of Columbia have enacted into law some form of psychotherapist privilege.” Id. at 12, 116 S.Ct. 1923. The Court reaffirmed the principle that “the policy decisions of the States bear on the question whether federal courts should recognize a new privilege,” id. at 12-13, and observed that, “[bjecause state legislatures are fully aware of the need to protect the integrity of the factfinding functions of their courts, the existence of a consensus among the States indicates that ‘reason and experience’ support recognition of the privilege,” id. at 13. Additionally,
given the importance of the patient’s understanding that her communications with her therapist will not be publicly disclosed, any State’s promise of confidentiality would have little value if the patient were aware that the privilege would not be honored in a federal court. Denial of the federal privilege therefore would frustrate the purposes of the state legislation that was enacted to foster these confidential communications.
Id. (footnote omitted).
Moreover, the privilege is justified independently by important private and public interests. As to the private interest served by the privilege, the Court recognized .that
a psychiatrist’s ability to help her patients “is completely dependent upon [the patients’] willingness and ability to talk freely. This makes it difficult if not impossible for [a psychiatrist] to function without being able to assure ... patients of confidentiality and, indeed, privileged communication. Where there may be exceptions to this general rule ..., there is wide agreement that confidentiality is a sine qua non for successful psychiatric treatment.” Advisory Committee’s Notes to Proposed Rules, 56 F.R.D. 183, 242 (1972).
[984]*984Id. at 10-11, 116 S.Ct. 1923 (other citation and internal quotation marks omitted).
As to the public interest served, the Court recognized that “[t]he psychotherapist privilege serves the public interest by facilitating the provision of appropriate treatment for individuals suffering the effects of a mental or emotional problem. The mental health of our citizenry, no less than its physical health, is a public good of transcendent importance.” Id. at 11, 116 S.Ct. 1923.
Despite its seemingly sweeping endorsement, the Court in Jaffee declined to delineate the “full contours” of the psychotherapist privilege. Id. at 18, 116 S.Ct. 1923. In a footnote that presaged the issues presented to us today, the Court noted:
Although it would be premature to speculate about most future developments in the federal psychotherapist privilege, we do not doubt that there are situations in which the privilege must give way, for example, if a serious threat of harm to the patient or to others can be averted only by means of a disclosure by the therapist.
Id. at 18 n. 19, 116 S.Ct. 1923.
We read that footnote as endorsing— albeit elliptically — a duty to disclose threats to the intended victim and to the authorities, the issue to which we turn next.2
B. Dr. Dieter properly disclosed the threats to the authorities.
Most states have a dangerous-patient exception to their psychotherapist-patient confidentiality laws. United States v. Hayes, 227 F.3d 578, 583 (6th Cir.2000). Some of these exceptions allow, and some require, a psychotherapist to disclose threats made by a patient during therapeutic sessions if the psychotherapist determines that the patient poses a risk of serious harm to self or others. This exception is often referred to as the Tarasoff duty, see, e.g., George C. Harris, The Dangerous Patient Exception to the Psychotherapist-Patient Privilege: The Tarasoff Duty and the Jaffee Footnote, 74 Wash. L.Rev. 33 (1999), after the California case that first introduced it. See Tarasoff v. Regents of Univ. of Cal., 17 Cal.3d 425, 131 Cal.Rptr. 14, 551 P.2d 334, 340 (1976) (“When a therapist determines, or pursuant to the standards of his profession should determine, that his patient presents a serious danger of violence to another, he incurs an obligation to use reasonable care to protect the intended victim against such danger. The discharge of this duty may require the therapist to take one or more of various steps, depending upon the nature of the case. Thus it may call for him to warn the intended victim or others likely to apprise the victim of the danger, to notify the police, or to take whatever other steps are reasonably necessary under the circumstances. ”).
Oregon recognizes this exception to the rule of confidentiality. Under Oregon law, a provider of mental health care may disclose “[i]nformation obtained in the course of diagnosis, evaluation or treatment of an individual that in the professional judgment of the health care services provider, indicates a clear and immediate danger to others or to society.” Or.Rev.Stat. [985]*985§ 179.505(12), amended by 2003 Or. Laws ch. 88 (H.B.2307).
In the circumstances of this case, we have no doubt that Dr. Dieter properly-disclosed the threats that Defendant had related regarding several specific individuals. Even if we were wrong in that conclusion, however, a state-law breach of psychotherapist-patient confidentiality would not necessarily lead to an abrogation of the federal testimonial privilege.
The Federal Rules of Evidence apply only to proceedings in federal court. See Fed.R.Evid. 101 (“These rules govern proceedings in the courts of the United States and before the United States bankruptcy judges and United States magistrate judges, to the extent and with the exceptions stated in rule 1101.”). Dr. Dieter’s disclosure to law enforcement personnel occurred long before any federal court proceedings had commenced. If her disclosure were improper, then Defendant might have a civil remedy in state court, see Humphers, 696 P.2d at 533 (“A number of decisions have held that unauthorized and unprivileged disclosure of confidential information obtained in a confidential relationship can give rise to tort damages.”), or Dr. Dieter might be answerable to the Oregon Board of Medical Examiners, which disciplines psychiatrists for violations of ethical rules, see Or.Rev. Stat. § 677.205 (2001). But Rule 501 is not implicated by an improper disclosure made outside of federal court proceedings.
The more difficult question under Rule 501 is what effect a proper disclosure may have: In other words, whether we should recognize a dangerous-patient exception to the federal testimonial privilege arising out of, or coextensive with, the dangerous-patient exceptions to states’ rules of confidentiality. We turn next to that question.
C. We decline to recognize a dangerous-patient exception to the federal testimonial privilege.
We are faced with an even split between the two circuits that have considered the question under Rule 501. That is, whether we decide that there is a dangerous-patient exception to the federal psychotherapist-patient privilege, or that there is not, we will have company.
The Tenth Circuit has said that a psychotherapist may testify about a threat made by a patient if “the threat was serious when it was uttered and ... its disclosure was the only means of averting harm ... when the disclosure was made.” United States v. Glass, 133 F.3d 1356, 1360 (10th Cir.1998). This is the approach that the district court and the three-judge panel took. Chase, 301 F.3d at 1024.
By contrast, the Sixth Circuit has held that there is no dangerous-patient exception to the psychotherapist-patient privilege. Hayes, 227 F.3d at 585-86. We agree with the Sixth Circuit for the four reasons that follow.
1. The States’Experiences
The Tarasoff duty, by definition, lifts the blanket of confidentiality covering psychotherapist-patient communications under state law. Ordinarily, however, the Tara-soff duty does not abrogate the testimonial privilege in state courts. Id. at 585. Generally, the psychotherapist may (or must) warn the authorities or the intended victims of a dangerous patient, but still may not testify to confidential communications in state-court proceedings.3 Of the states [986]*986in the Ninth Circuit, only California has an evidentiary dangerous-patient exception. See id. (explaining that California is alone in the nation in enacting a dangerous-patient exception in its law of evidence). In California, a psychotherapist not only must disclose to authorities or intended victims the existence of a dangerous patient, but also may testify to threats made in the course of therapy. See Cal. Evid. Code § 1024 (“There is no privilege under this article if the psychotherapist has reasonable cause to believe that the patient is in such mental or emotional condition as to be dangerous to himself or to the person or property of another and that disclosure of the communication is necessary to prevent the threatened danger.”).
Almost all the states, then, recognize the distinction between confidentiality (which is affected by the Tarasoff duty) and testimonial privilege (which is not). In Oregon, where Defendant resided, received psychiatric treatment, and was convicted, the distinction has been explained this way by the state’s supreme court:
It is important to distinguish between the evidentiary privilege which is claimed by a patient, or a psychotherapist in behalf of a patient (OEC 504(3)), to prevent disclosure of confidential information at trial, and the discretionary authority of a public health care provider or any ethical obligation that a licensed psychotherapist may have to notify the police or other proper authority in order to aid a victim or warn of future dangerousness. The public interest to be served by notifying the police, in most cases, could be achieved by divulging only that information needed to show why a clear and immediate danger is believed to exist. It would rarely justify the full disclosure of the patient’s confidences to the police, and never justify a full disclosure in open court, long after any possible danger has passed.
State v. Miller, 300 Or. 203, 709 P.2d 225, 236 (1985) (footnote omitted). Had Defendant been prosecuted in state court, Dr. Dieter could not have testified about what Defendant told her during therapeutic sessions, notwithstanding her permissible disclosure of threats to the authorities. See also State v. Wilkins, 125 Idaho 215, 868 P.2d 1231, 1235 (1994) (defining Idaho’s testimonial privilege and reversing a conviction where a psychotherapist testified at sentencing to threats made by the defendant during therapy).
The states’ experiences are relevant in two ways. First, the states’ experiences are instructive in themselves, see Jaffee, 518 U.S. at 12, 116 S.Ct. 1923, especially when they are nearly uniform over a significant period of time. Second, a dangerous-patient exception affirmatively would weaken state confidentiality laws. The Supreme Court reasoned in Jaffee that refusing to recognize a federal psychotherapist-patient privilege would undermine the states’ confidentiality laws. Id. at 13, 116 S.Ct. 1923. Exceptions to the federal privilege, where state laws contain no parallel exception, would have a similar effect. A state’s promise of confidentiality has less value if the patient knows that an exception to the privilege applies in federal court.
2. Differing Purposes of State Confidentiality Laws and the Federal Testimonial Privilege
As we have just explained, the states themselves disconnect confidentiality from the testimonial privilege. Similarly, the Sixth Circuit has opined that it would be a mistake to view
the standard of care exercised by a treating psychotherapist prior to complying with (or, for that matter, failing to comply with) a state’s “duty' to protect” requirement is somehow pertinent [987]*987to the applicability of the psyehothera-pisVpatient privilege in criminal proceedings. We think there is little correlation between those two inquiries.
Hayes, 227 F.3d at 583. The Sixth Circuit continued, saying that it saw
only a marginal connection, if any at all, between a psychotherapist’s action in notifying a third party (for his own safety) of a patient’s threat to kill or injure him and a court’s refusal to permit the therapist to testify about such threat (in the interest of protecting the psychotherapist/patient relationship) in a later prosecution of the patient for making it. State law requirements that psychotherapists take action to prevent serious and credible threats from being carried out serve a far more immediate function than the proposed “dangerous patient” exception. Unlike the situation presented in Tarasoff, the threat articulated by a defendant [who makes a threat in the course of therapy] is rather unlikely to be carried out once court proceedings have begun against him.
Id. at 583-84. We agree with the Sixth Circuit for two reasons, one theoretical and the other practical.
As to the first of those considerations, analytically there is little connection between a psychotherapist’s state-imposed obligation to report a dangerous patient at the time the patient makes a threat, on the one hand, and the later operation of the federal testimonial privilege, on the other. The Tarasoff duty is justified on the ground of protection; the societal benefit from disclosing the existence of a dangerous patient out-weighs the private and public cost of the deleterious effect on the psychotherapist-patient relationship. By contrast, ordinarily testimony at a later criminal trial focuses on establishing a past act. There is not necessarily a connection between the goals of protection and proof. If a patient was dangerous at the time of the Tarasoff disclosure, but by the time of trial the patient is stable and harmless, the protection rationale that animates the exception to the states’ confidentiality laws no longer applies.
Second, as a practical matter, the fact that different states have different standards regarding when a psychotherapist must (or may) breach confidentiality by disclosing a patient’s threats counsels against hinging the Jaffee testimonial privilege on the protective disclosure laws of the states. For example, Washington’s exception to the confidentiality requirement allows for disclosure by a psychotherapist “[t]o appropriate law enforcement agencies and to a person, when the identity of the person is known to the public or private agency, whose health and safety has been threatened, or who is known to have been repeatedly harassed, by the patient.” Wash. Rev.Code § 71.05.390(10) (emphasis added). By contrast, in California, when a psychotherapist “determines, or pursuant to the standards of his profession should determine, that his patient presents a serious danger of violence to another, he incurs an obligation to use reasonable care to protect the intended victim against such danger.” Tarasoff, 131 Cal.Rptr. 14, 551 P.2d at 340.
Those standards are materially different. In Washington, a therapist has permission to disclose conversations if the patient has repeatedly harassed someone, even if the psychotherapist does not think that the patient presents a “serious danger of violence.” In California, a patient who engages in similar harassment retains the confidentiality because the patient does not present a “serious danger of violence.” If the federal evidentiary privilege were tied to the states’ disclosure laws, then similarly situated patients would face different rules of evidence in federal criminal trials. The Washington [988]*988patient’s therapist could testify under a dangerous-patient exception (because his therapist permissibly had disclosed a communication under state law), while the California patient’s psychotherapist would be forbidden from testifying. The Federal Rules of Evidence should apply uniformly and not vary depending on the state in which the defendant resides. See United States v. DeWater, 846 F.2d 528, 530 (9th Cir.1988) (“Using federal rules of evidence and procedure and case law promotes the uniform disposition of criminal matters in the federal system.”); see also Lippay v. Christos, 996 F.2d 1490, 1497 (3d Cir.1993) (discussing “Congress’ intent that the Federal Rules of Evidence have uniform nationwide application”); Boren v. Sable, 887 F.2d 1032, 1038 (10th Cir.1989) (stating that “the Federal Rules of Evidence are intended to have uniform nationwide application”).
The strongest argument in favor of tying a dangerous-patient exception to state laws is that, “when the [psychotherapist] has specifically informed the patient that the [psychotherapist] will not keep the communications confidential, there is no barrier to that person testifying.” Hayes, 227 F.3d at 587 (Boggs, J., dissenting). The logic of this argument is that, if the patient knows that the psychotherapist can disclose threats to third parties that the patient communicates during treatment, then the patient has no expectation of confidentiality in the first place when communicating the threats; therefore, there is no reason to treat such communications as “privileged.”
This view is a cousin to a common analysis of the waiver of a privilege. As the New York Court of Appeals observed almost one hundred years ago, “when a secret is out, it is out for all time, and cannot be [caught again] like a bird, and put back in its cage.” People v. Bloom, 193 N.Y. 1, 85 N.E. 824, 826 (1908); see also 2 McCormick on Evidence § 93, at 371-72 (5th ed. 1999) (“Finding waiver in situations in which forfeiture of the privilege was not subjectively intended by the holder is consistent with the view, expressed by some cases and authorities, that the essential function of the privilege is to protect a confidence which, once revealed by any means, leaves the privilege with no legitimate function to perform.”).
We are unpersuaded by this argument for two reasons. First, it relies to some extent on a fiction that the patient knows that a disclosure for one purpose (warning a potential target of violence) is a disclosure for all purposes (including incriminating testimony in a federal criminal trial).4 Such a conclusion is not a logical necessity; a communication can be “not confidential” under state law, but still “privileged” under the Federal Rules of Evidence.5 Second, to the extent that a patient actually does know the law and the rules of evidence, the legal rule itself, whatever .it may be, will govern the patient’s expectations. If, for example, the operative legal rule is [989]*989that a therapist may disclose threats in order to warn intended victims, but may not testify to the threats in federal court— the analogue to the rule in most states— that is the rule that the patient will assume is in effect.
B. The 1972 Proposed Rule
In 1972 the Chief Justice of the United States, on the recommendation of the Judicial Conference Advisory Committee on the Rules of Evidence, submitted nine proposed testimonial privileges to Congress. See Jaffee, 518 U.S. at 8 n. 7, 116 S.Ct. 1923; see also Huston Combs, Note, Dangerous Patients: An Exception to the Federal Psychotherapist-Patient Privilege, 91 Ky. L.J. 457, 459-60 (2003). One of these privileges, embodied in Proposed Rule 504, was a psychotherapist-patient privilege. Proposed Federal Rules of Evidence, 56 F.R.D. 183, 240-41 (1972). The Proposed Rule establishing that privilege also created three exceptions: proceedings to hospitalize a patient for mental illness, proceedings to examine the mental or emotional condition of the patient, and proceedings in which the patient’s mental or emotional condition is relevant to a claim or defense. Id. at 241.
Conspicuously absent from the list was a dangerous-patient exception. One commentator has explained that the “omission was deliberate. The exceptions allowed were patterned after those in [a] then-existing Connecticut statute.” Harris, 74 Wash. L.Rev. at 37. The Proposed Rules cited an article by two authors of the Connecticut statute. See 56 F.R.D. at 243-44 (citing Abraham S. Goldstein & Jay Katz, Psychiatrist-Patient Privilege: The GAP Proposal and the Connecticut Statute, 36 Conn. B.J. 175, 182 (1962)). Professors Goldstein and Katz wrote:
It should be noted that our committee deliberately chose not to write a “future crime” exception into the bill. Its members were persuaded that, as a class, patients willing to express to psychiatrists their intention to commit crime are not ordinarily likely to carry out that intention. Instead, they are making a plea for help. The very making of these pleas affords the psychiatrist his unique opportunity to work with patients in an attempt to resolve their problems. Such resolutions would be impeded if patients were unable to speak freely for fear of possible disclosure at a later date in a legal proceeding.
Goldstein & Katz, 36 Conn. B.J. at 188.
As explained by one commentator,
[t]his logic was apparently persuasive to the federal Advisory Committee. As explained by [Weinstein]: “[although some ... have argued that the need for disclosure is paramount when possible harm is threatened, [Proposed Rule] 504 proceeds on the assumption that less harm will ensue if patients feel free to ventilate their intentions.”
Harris, 74 Wash. L.Rev. at 38 (quoting 2 Jack B. Weinstein & Margaret A. Berger, Weinstein’s Federal Evidence § 504[05], at 504-27 (2d ed.1996, Release No. 35-8/89)); see also Harris, 74 Wash L.Rev. at 67-68 (“The Supreme Court in Jaffee, following the lead of the Federal Rules Advisory Committee and state legislatures, made a policy judgment that the value of protecting the confidentiality of the psychotherapist-patient relationship outweighs the evidentiary value of admitting a patient’s confidential statements for the purpose of proving criminal conduct by the patient. The powerful and salutary impulse to protect potential victims that gave rise to the Tarasoff duty to warn should not be allowed to distort the consistent application of that policy judgment. Indeed, the rationale supporting that judgment includes the belief that protection of the therapeutic relationship will result in less patient violence.”).
[990]*990Of course, Congress ultimately chose to enact the more open-ended Rule 501 rather than the proposed rule. Nevertheless, because “the Supreme Court has officially recognized the psychotherapist-patient privilege, and cited favorably to [Proposed Rule 504] as initially proposed, the contents of the [Proposed Rule] have considerable force and should be consulted when the psychotherapist-patient privilege is invoked.” 3 Weinstein’s Federal Evidence § 504.02, at 504-7 (footnote omitted).
4. Public Policy
Finally, in exercising our common-law function as we consider whether to recognize a dangerous-patient exception under Rule 501, we turn to the policies underlying psychotherapist-patient confidentiality and the states’ disclosure exceptions. The confidentiality laws, and the testimonial privilege, are designed to assist the individual patient who has sought help and, on a larger scale, to improve public health. Jaffee 518 U.S. at 11-12, 116 S.Ct. 1923. Any exception necessarily has some adverse effect on the candor that the psychotherapist-patient privilege is meant to encourage, because patients will be more reluctant to divulge unsavory thoughts or urges if they know that the therapist may be required to testify about the content of therapeutic sessions.
The justification for the dangerous-patient exception to states’ confidentiality rules is, of course, the health and safety of the potential victim of the patient. The potential victim’s well-being is as important as that of the patient. The difficult question is how to balance the patient’s need for candor, in service of therapy, against the potential victim’s need for protection.
As noted, the states have balanced those needs at the time of the threat by requiring, or at least permitting, disclosure to the potential victim and to the authorities. The issue is somewhat more subtle when we reach the time of a trial at which the threats, originally disclosed during a therapeutic session, are relevant to a federal criminal proceeding. What marginal harm is done to the psychotherapist-patient relationship by the additional disclosure, and what marginal protection is offered to society?
We know that the initial disclosure to the target or to the authorities can be damaging to the psychotherapist-patient relationship. But we think that a patient will retain significantly greater residual trust when the therapist can disclose only for protective, rather than punitive, purposes. In other words, the marginal additional harm to the relationship is significant. As the Sixth Circuit expressed it:
[Recognition of a “dangerous patient” exception surely would have a deleterious effect on the “atmosphere of confidence and trust” in the psychotherapist/patient relationship. While early advice to the patient that, in the event of the disclosure of a serious threat of harm to an identifiable victim, the therapist will have a duty to protect the intended victim, may have a marginal effect on a patient’s candor in therapy sessions, an additional warning that the patient’s statements may be used against him in a subsequent criminal prosecution would certainly chill and very likely terminate open dialogue. See, e.g., Gregory B. Leong, et al, The Psychotherapist as Witness for the Prosecution: The Criminalization of Tarasojf AM. J. PSYCHIATRY 149:8, at 1011, 1014 (Aug.1992). Thus, if our Nation’s mental health is indeed as valuable as the Supreme Court has indicated, and we think it is, the chilling effect that would result from the recognition of a “dangerous patient” exception and its [991]*991logical consequences is the first reason to reject it.
Hayes, 227 F.3d at 584-85.
On the other side of the equation, the obvious good afforded by a dangerous-patient exception is that, if psychotherapists were permitted to testify in federal criminal cases to matters discussed with patients during treatment, it is more likely that patients who have threatened others will be convicted. If convicted, the patient may be incarcerated, and incarceration is one way to ensure protection of the intended victim and others. However, the additional protection that would come from the psychotherapists’ testimony is not as great as it may seem at first blush.
We note, first, that there are many situations in which the privilege simply would not apply at all. For example, if a patient engaged in a criminal act, such as an assault, at the doctor’s office, no privilege would apply because the privilege protects only communications. See Jaffee, 518 U.S. at 15, 116 S.Ct. 1923 (“[W]e hold that confidential communications between a licensed psychotherapist and her patients in the course of diagnosis or treatment are protected from compelled disclosure under Rule 501 of the Federal Rules of Evidence.”).
Second, it usually will be the case that there is other evidence of the crimes in question. The privilege does not apply to non-psychotherapists to whom similar threats may have been uttered. See Jaffee, 518 U.S. at 9-10, 116 S.Ct. 1923 (“[T]he question we address today is whether a privilege protecting confidential communications between a psychotherapist and her patient promotes sufficiently important interests to outweigh the need for probative evidence.... Both ‘reason and experience’ persuade us that it does.” (emphasis added) (citation and internal quotation marks omitted)).
Third, the federal testimonial privilege would not apply in state court proceedings, including commitment proceedings.6 States generally allow psychotherapists to testify in civil commitment proceedings, which are designed in part to detain and deter mentally ill persons who are dangerous. Oregon has such a provision. See Or. Evid.Code § 504(4)(d) (providing that there is no privilege for confidential communications, or records thereof, when the statutes pertaining to commitment allow the use of such evidence).
Finally, although incarceration is one way to eliminate a threat of imminent harm, in many cases treatment is a longer-lasting and more effective solution. A criminal conviction with the help of a psychotherapist’s testimony is almost sure to spell the end of any patient’s willingness to undergo further treatment for mental health problems. See Hayes, 227 F.3d at 585 (“Once in prison, even partly as a consequence of the testimony of a therapist to whom the patient came for help, the probability of the patient’s mental health improving diminishes significantly....”).
On balance,7 we conclude that the gain [992]*992from refusing to recognize a dangerous-patient exception to the psychotherapist-patient testimonial privilege in federal criminal trials outweighs the gain from recognizing the exception.
5. Conclusion
A dangerous-patient exception to the federal psychotherapist-patient testimonial privilege would significantly injure the interests justifying the existence of the privilege; would have little practical advantage; would encroach significantly on the policy prerogatives of the states; and would go against the experience of all but one of the states in our circuit, as well as the persuasive Proposed Rules. We therefore decline to recognize a dangerous-patient exception to the federal psychotherapist-patient privilege.
Dr. Dieter testified about some of her conversations with Defendant during therapeutic sessions. Because Defendant’s statements were made for the purpose of obtaining treatment, and because there is no dangerous-patient exception to the federal privilege that otherwise applies, see Jaffee, 518 U.S. at 15, 116 S.Ct. 1923, the admission of Dr. Dieter’s testimony about Defendant’s communications to her was erroneous.8
D. The error in admitting Dr. Dieter’s testimony was harmless.
Defendant was convicted only on Count I, the making of a threat against the FBI agents who were en route to his home. This threat was communicated to a telephone operator at Kaiser Permanente. Defendant does not argue that his communications to the operators were confidential or that the operators are subject to an evidentiary privilege.9 Count I, which involved only the threat that Defendant conveyed to a Kaiser Permanente operator, rested on the operator’s testimony.
The threats to which Dr. Dieter testified formed the basis of Count II, on which Defendant was acquitted. We have held that Dr. Dieter’s testimony was admitted in violation of the federal psychotherapist-patient privilege. Our remaining task is to determine whether that error was harmless.
Because the answer will affect our harmless-error analysis, we pause to con-' sider whether the evidence of other threats was properly admitted in the gov[993]*993ernment’s case concerning Count II. We believe that it was, for the reasons stated in the three-judge panel’s opinion. Chase, 301 F.3d at 1026-31.
“[Harmless error analysis applies to the improper admission of evidence, and reversal is proper only if the government cannot show that the error was more probably than not harmless.” United States v. Beckman, 298 F.3d 788, 793 (9th Cir.2002). Because a violation of the psychotherapist-patient privilege is not a constitutional error, the government must show that the prejudice resulting from the error was “more probably than not harmless.” See United States v. Bauer, 132 F.3d 504, 510 (9th Cir.1997). To meet that standard, the government must “show a fair assurance that the verdict was not substantially swayed by the error.” Id. (internal quotation marks omitted).
We are satisfied that the admission of Dr. Dieter’s testimony was harmless error. The jury acquitted Defendant on Count II, which related to the threats that Defendant communicated to Dr. Dieter during therapeutic sessions, a result that suggests, at a minimum, that she did not influence the jury unduly. Dr. Dieter’s testimony had no bearing on Count I, on which the jury convicted Defendant. Count I arose entirely from Defendant’s expression of threats to a Kaiser Permanente telephone operator. On this record, we believe that the result on Count I surely would have been the same even without Dr. Dieter’s testimony. That being so, the erroneous admission of her testimony did not prejudice Defendant.
AFFIRMED.