with whom WILLIAMS, Circuit Judge, joins, concurring in part and dissenting in part.1
At this late stage in the litigation, we are now turning to a fundamental question: Are we going to evaluate claims for terrorism-inflicted injuries using traditional legal standards, or are we going to rewrite tort law on the ground that “terrorism is sui generis ”? Ante at 698. My colleagues in the majority have opted to “relaxf ]” — I would say eliminate — the basic tort requirement that causation be proven, believing that “otherwise there would be a wrong and an injury but no remedy because the court would be unable to determine which wrongdoer inflicted the injury.” Ante at 697. The choice is a false one. The panel took pains to identify a number of ways in which the plaintiffs might establish a causal link between the defendants’ financial contributions to (and other support for) Hamas and the murder of David Boim. Boim II, 511 F.3d at 741-43. It is not the case that the plaintiffs were unable show causation, it is rather that they did not even make an attempt; and that was the purpose of the panel’s decision to remand the case.2 But rather than requiring the plaintiffs to present evidence of causation and allowing the factfin-der to determine whether causation has been shown, the majority simply deems it a given, declaring as a matter of law that any money knowingly given to a terrorist organization like Hamas is a cause of terrorist activity, period. This sweeping rule of liability leaves no role for the factfinder to distinguish between those individuals and organizations who directly and purposely finance terrorism from those who are many steps removed from terrorist activity and whose aid has, at most, an indirect, uncertain, and unintended effect on terrorist activity. The majority’s approach treats all financial support provided to a terrorist organization and its affiliates as support for terrorism, regardless of whether the money is given to the terrorist organization itself, to a charitable entity controlled by that organization, or to an intermediary organization, and regardless of what the money is actually used to do.
*706The majority’s opinion is remarkable in two additional respects. By treating all those who provide money and other aid to Hamas as primarily rather than secondarily liable — along with those who actually commit terrorist acts — the majority eliminates any need for proof that the aid was given with the intent to further Hamas’s terrorist agenda. Besides eliminating yet another way for the factfinder to distinguish between those who deliberately aid terrorism from those who do so inadvertently, this poses a genuine threat to First Amendment freedoms. Finally, the majority sustains the entry of summary judgment on a basic factual question — Did Hamas kill David Boim? — based on an expert’s affidavit that both relies upon and repeats multiple examples of hearsay. Rather than sustain the panel’s unexceptional demand that the expert’s sources be proven reliable, consistent with Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 597, 113 S.Ct. 2786, 2799, 125 L.Ed.2d 469 (1993), the majority gives its blessing to circumventing the rules of evidence altogether.
Thus, although I concur in the decision to remand for further proceedings as to HLF, I otherwise dissent from the court’s decision.
1.
One point of clarification at the outset. The majority’s opinion reads as though the defendants were writing checks to Hamas, perhaps with a notation on the memo line that read “for humanitarian purposes.” If indeed the defendants were directing money into a central Hamas fund out of which all Hamas expenses — whether for humanitarian or teiTorist activities — were paid, it would be easy to see that the defendants were supporting Hamas’s terrorism even if their contributions were earmarked for charity. In fact, the case is not as simple as that. For example, much of the money that defendant HLF provided to Hamas apparently was directed not to Hamas per se but to a variety of zakat committees and other charitable entities, including a hospital in Gaza, that were controlled by Ha-mas. See Holy Land Found, for Relief & Dev. v. Ashcroft, 219 F.Supp.2d 57, 70-71 (D.D.C.2002), j. aff'd, 333 F.3d 156 (D.C.Cir.2003).3 I gather that this is a distinction without a difference in the majority’s view, and certainly I agree that if the zakat committees and other recipients of HLF’s funding were mere fronts for Hamas or were used to launder donations targeted for Hamas generally, then those donations ought to be treated as if they were direct donations to Hamas itself.4 But to the extent that these Hamas subsidiary organizations actually were engaged solely in humanitarian work and HLF was sending its money to those subsidiaries to support that work, HLF is one or more significant steps removed from the direct financing of terrorism and the case for HLF’s liability for terrorism is, in my view, a much less compelling one. Defendant AMS is yet another step removed, in that AMS is alleged to have contributed money not to Hamas but to HLF.
Moreover, the type of support that can give rise to civil liability is not limited to financial support. As the panel discussed
*707in Boim I, civil liability under section 2333(a) can result from the provision of “material support or resources” to terrorism and to terrorist organizations as prohibited by 18 U.S.C. §§ 2339A and 2339B, see 291 F.3d at 1012-17, and “material support or resources” is defined broadly to include not only weapons and money but “any property, tangible or intangible, or service,” including such things as lodging, expert advice, training, and personnel. § 2339A(b)(1). Notably, the plaintiffs have sought to hold AMS liable, and the district court found it liable, not simply for the financial support it provided to HLF, but for various types of pro-Hamas advocacy, such as hosting Hamas speakers at its conferences, publishing sympathetic editorials in its newsletter, and the like. See Boim v. Quranic Literacy Inst., 340 F.Supp.2d 885, 908-13 (N.D.Ill.2004).
So the majority’s rule has the potential to sweep within its reach not only those who write checks to Hamas and the organizations that it controls but also individuals and groups who support Hamas and its affiliates in myriad other ways, including those who advocate on Hama’s behalf. My point is not that there is no case to be made for imposing liability on such supporters for Hamas’s terrorist acts. My point is simply that the basis for their liability is not nearly as clean and straightforward as it might seem from the majority’s opinion.
2.
The majority has chosen to evaluate the prospective liability of the defendants in this case through the lens of primary liability, reasoning that those who provide financial and other aid to terrorist organizations are themselves engaging in terrorism and thus may be held liable on the same basis as those who actually commit terrorist acts.5 In formulating its theory of primary liability, the majority relies in part upon section 2331(l)’s definition of “international terrorism” and partly upon section 2339A(a)’s criminal proscription against providing material support or resources to terrorists. Treating the defendants as primarily rather than secondarily liable enables the majority to accomplish two things: First, it compensates for what the majority believes was Congress’s failure in section 2333(a) to authorize the imposition of secondary liability on those who aid or abet terrorist acts or conspire with terrorists. Second, it eliminates any need for proof of a defendant’s intent to support terrorism; a defendant’s knowledge that it is providing aid to an organization that engages in terrorism is deemed enough to hold that defendant liable for the organization’s terrorist acts.
*708For the reasons outlined in the Boim I opinion, I continue to believe that Congress when it enacted section 2333(a) subjected to civil liability not only those who engage in terrorism but also those who aid or abet terrorism. 291 F.3d at 1016-21. The government as an amicus curiae has expressed agreement with that view. The secondary liability framework is a much more natural fit for what the defendants here are alleged to have done and as I shall discuss below, the elements of aiding and abetting serve a useful function in distinguishing between those who intend to aid terrorism and those who do not.
But even if I am wrong about the availability of secondary liability under section 2333(a), I have my doubts about the viability of the majority’s theory of primary liability. For there are conceptual problems with this approach, particularly as it is applied in this case. These problems may help to explain why the plaintiffs have long since abandoned any theory of primary liability and have relied solely on theories of secondary liability in this appeal. And it makes it all the more extraordinary that this court has gone out on a limb to craft a liability standard that none of the parties has advocated.
The majority first posits that the defendants’ alleged conduct falls within section 2331(l)’s definition of “international terrorism,” ante at 689-90, but the fit is by no means perfect. In full, the statutory definition of the term reads as follows:
[T]he term “international terrorism” means activities that—
(A) involve violent acts or acts dangerous to human life that are a violation of the criminal laws of the United States or of any State, or that would be a criminal violation if committed within the jurisdiction of the United States or of any State;
(B) appear to be intended—
(i) to intimidate or coerce a civilian population;
(ii) to influence the policy of a government by intimidation or coercion;
(iii) to affect the conduct of a government by mass destruction, assassination, or kidnapping; and
(C)occur primarily outside the territorial jurisdiction of the United States, or transcend national boundaries in terms of the means by which they are accomplished, the persons they appear intended to intimidate or coerce, or the locale in which their perpetrators operate or seek asylumf.]
18 U.S.C. § 2331(1). The language of this definition certainly is broad enough to reach beyond bomb-throwers and shooters to include those who provide direct and intentional support to terrorists: someone who ships arms to a terrorist organization, for example, easily could be thought to be engaging in activity that “involve[s] violent acts or acts dangerous to human life” as set forth in section 2331(1)(A). See Boim I, 291 F.3d at 1014-15. But it is far from clear that sending money to a Hamas-controlled charitable organization, for example, is on par with that type of direct support for terrorism. It may be, as the majority posits, that donations to Hamas’s humanitarian wing indirectly aid its terrorism by freeing up other funds for terrorism, by giving cover to Hamas, and by otherwise enhancing Hamas’s image. But it is difficult if not implausible to characterize donations that are earmarked and used for humanitarian work as violent or life-threatening acts as referenced in section 2331(1)(A). Nor is it evident (to say the least) that financially supporting a Ha-mas-affiliated charity is an act that “appeals] to be intended” to have the sorts of coercive or intimidating effects on govern*709ment policy or upon a civilian population as described in section 2331(1)(B).
It may be more plausible to say, as the majority does, that one who provides financial support to Hamas, even to its charitable subsidiaries, is “providing] material support or resources” to Hamas’s terrorist acts in violation of section 2339A(a) by increasing the heft of Hamas’s purse. See ante at 690-91. But that theory too has its problems. The language of section 2339A(a) requires that the material support or resources be given with the knowledge or intent that they “are to be used in preparation for, or in carrying out” one of a number of specified crimes, including as relevant here the killing of American citizens. (Emphasis mine.); see ante at 690, citing 18 U.S.C. § 2332. In other words, the donor must at least know that the financial or other support he lends to Ha-mas will be used to commit terrorist acts. In Boim I, the panel agreed that giving money to Hamas with the purpose of financing its terrorism would both violate section 2339A(a) and give rise to civil liability under section 2333. 291 F.3d at 1012-16. But at that early stage of this litigation, the Boims had a straightforward and direct theory that Hamas’s American contributors (including HLF) intended for their money be used to support terrorism, that the zakat committees and other humanitarian organizations to which these contributors were sending their money were mere fronts for Hamas, and that the money received by these front organizations was laundered and funneled into Ha-mas’s coffers to fund terrorist activity, including the attack that took David Boim’s life. See id. at 1004. That theory was consistent with the express terms of section 2339A(a). But that is no longer the Boims’ theory (they have long since abandoned it in favor of aiding and abetting and conspiracy), nor is it the majority’s. The majority posits that any money given to a Hamas affiliate, even if it is given with a benign intent and even if it is actually put to charitable use, furthers Hamas’s terrorism in one way or another. Ante at 698. Even if that is so, not all donors will know or intend that their contributions will be used to commit the sorts of criminal acts identified in section 2339A(a). And what the statute proscribes is the knowing or intentional support of specific terrorist acts, not the knowing support of a terrorist organization. If nothing else, the defendants’ contributions to charitable organizations controlled by Hamas would present a factual question as to whether the defendants knew that they were supporting the murder of American citizens or any of the other crimes listed in section 2339A(a).
3.
Causation, as the majority acknowledges, is a staple of tort law, ante at 695, and yet the majority relieves the plaintiffs of any obligation to demonstrate a causal link between whatever support the defendants provided to Hamas and Hamas’s terrorist activities (let alone David Boim’s murder in particular). Instead, the majority simply declares as a matter of law that any money given to an organization like Hamas that engages in both terrorism and legitimate, humanitarian activity, necessarily enables its terrorism, regardless of the purpose for which the money was given or the channel through which the organization received it. “Anyone who knowingly contributes to the nonviolent wing of an organization that he knows to engage in terrorism is knowingly contributing to the organization’s terrorist activities.” Ante at 698. This is judicial activism at its most plain. The majority offers no rationale for relieving the plaintiffs of the burden of showing causation, and there is none that I can discern. The panel in Boim II expressly disavowed any requirement that *710the Boims link specific donations or other acts of support to David Boim’s murder in particular. 511 F.3d at 741. But it did insist on proof that the types of support the defendants were alleged to have given Hamas were, in fact, a cause of Hamas’s terrorism. Id. at 741-43. The panel outlined multiple ways in which the plaintiffs might show that support given to Hamas, even donations to its humanitarian activities, furthers its terrorist agenda, such that it could be considered a cause of David Boim’s murder. Id. Someone familiar with Hamas’s financial structure, or with the financing of terrorism generally, presumably could provide that sort of testimony. But the majority is not even conditioning liability on expert opinion that might link the various types of support provided to Hamas with its terrorist acts. Expert testimony as to the ways in which even aid to Hamas’s humanitarian wing enables terrorism would be subject to adversarial testing and the judgment of the factfinder based on the totality of the evidence put before the court. But rather than subject the notion of causation to those checks, the majority, acting as though we ourselves are experts, simply declares causation to be a given that cannot be challenged. Liability under the majority’s announced rule is sweeping: one who gives money to any Hamas entity, even if it is a small donation to help buy an x-ray machine for a Hamas hospital, is liable from now until the end of time for any terrorist act that Hamas might thereafter commit against an American citizen outside of the United States. (The majority itself acknowledges that under its approach a contribution to a terrorist organization in 1995 might render the donor liable for the murder of an American citizen committed by that organization fifty years later. Ante at 700.) This type of across-the-board judgment is out of place in the realm of torts. As an appellate court, it is our job to articulate a framework of liability under the statute and thereafter leave it to the parties to present evidence pursuant to that framework and to the factfinder to determine whether or not liability has been established. Where it is open to question, as I believe it is, whether even humanitarian support given to Hamas, to its charitable subsidiary, or to a hospital or other institution that receives funding from Hamas, actually contributes to Hamas’s terrorist activities, it should be left to factfinding in individual cases (subject, of course, to appellate review) to evaluate, based on the evidence presented in those cases, what types of support to Hamas and its affiliated entities actually cause terrorism. Cf. Thorogood v. Sears, Roebuck & Co., 547 F.3d 742, 744-45 (7th Cir.2008) (where the claims of multiple plaintiffs present complex factual questions, it is preferable to let those claims be resolved via individual lawsuits, so that the aggregate outcome fairly reflects the uncertainty of the plaintiffs’ claims, rather than risk error by having the issue resolved on a class-wide basis by a single trier of fact).
The majority’s decision to carve out an exception to its sweeping liability rule for non-governmental organizations like the Red Cross and Doctors Without Borders who provide humanitarian aid to individuals affiliated with Hamas lays bare the weakness of the rule’s analytical underpinnings.6 Providing medical care on the bat*711tlefield to individuals that one knows are Hamas terrorists (see ante at 699) undoubtedly would have the effect of aiding Hamas’s terrorism — patching up an injured terrorist enables him to strike again. I do not doubt that such aid could be given for noble and compassionate reasons, but neither do I doubt that from the standpoint of the Israelis whom Hamas targets, the knowing provision of medical care to individual terrorists could be and would be understood as aid to terrorism. One can also imagine scenarios in which medical aid could be provided for ignoble and devious reasons. Cf. United States v. Alvarez-Machain, 504 U.S. 655, 657, 112 S.Ct. 2188, 2190, 119 L.Ed.2d 441 (1992) (physician indicted for participating in the kidnap and murder of agent of Drug Enforcement Administration by helping to prolong captured agent’s life so that others could continue to interrogate and torture him). Yet, for no apparent reason other than our own sense that organizations like the Red Cross and Doctors Without Borders are good and do good, the majority simply declares them exempt from the broad liability standard that it has announced. Ante at 699. On the other hand, any other individual or organization that gives to a Hamas-controlled charity is deemed liable, regardless of whether the money is given with a humanitarian purpose and regardless of whether the money is, in fact, put to humanitarian use. So one cannot fund the construction of a Hamas hospital, buy the hospital an x-ray machine, or volunteer her medical services to the hospital, because this is not providing direct aid to individuals in the manner of the Red Cross. My colleagues reason that there is a distinction between providing aid to an individual, even if he is terrorist, and aid to a terrorist organization. Ante at 699. But to my mind, that is a distinction without a difference when one knows that the individual being aided is engaged in terrorism (or is recklessly indifferent to that possibility). For example, the majority notes that one way in which Hamas uses its social welfare activities to reinforce its terrorist agenda is by providing economic aid to the families of killed, wounded, or captured Hamas terrorists, which ensures the continued loyalty of these family members to Hamas. Ante at 698. In that respect, one who donates money to Hamas in order to fund such payments thus could be thought to be promoting terrorism. Yet, the same could be said of a donor who instead makes payments directly to the family members of terrorists rather than giving the money to Hamas. Indeed, that is exactly what HLF is alleged to have done (among other things). See Boim II, 511 F.3d at 722; Holy Land Found, for Relief & Dev., 219 F.Supp.2d at 71-73. So providing this type of aid to individuals, rather than to Hamas, would be accomplishing the same end, notwithstanding the fact that the donor was giving aid to individuals rather than to a terrorist organization. See Singh-Kaur v. Ashcroft, 385 F.3d 293, 301 (3d Cir.2004) (providing food and shelter to militant Sikhs who had committed or planned to commit terrorist acts constituted material support for terrorism). The distinction between aiding an organization and aiding individual members of that organization does not hold up.
It is only the majority’s sweeping rule of liability that puts humanitarian organizations like Doctors Without Borders in peril and that forces the majority to carve out *712an unprincipled exemption for such organizations. If a plaintiff were required to establish a donor’s intent to aid terrorism, along with a causal link between the aid provided and terrorist activity, then the factfinder would be able to draw reasoned, pragmatic distinctions (subject, of course, to appellate review) between those defendants who are truly enabling terrorism and those who are not.
4.
The secondary liability framework that we outlined in Boim I, and on which the plaintiffs built their entire ease against the defendants, provides a more grounded and effective way of identifying and distinguishing between the types of support and supporters that actually aid terrorism and those that do not. As the panel recognized, those who aid and abet Hamas’s terrorism can be held liable to the same extent as those who commit the terrorist acts. Boim I, 291 F.3d at 1016-21. But in addition to showing knowledge of Hamas’s terrorist activity and the provision of financial or other support to Hamas, aiding and abetting would require proof of an intent to help Hamas’s terrorist activities succeed. Id. at 1021, 1023.
Proof of intent would serve two important functions. First, it would serve to single out the most culpable of Hamas’s financiers and other supporters by focusing on those who actually mean to contribute to its terrorist program, as opposed to those who may unwittingly aid Hamas’s terrorism by donating to its charitable arm. I think it would be possible to infer the intent to further terrorism in a number of scenarios. Donations to Hamas itself have been a crime since 1997, for example, when Hamas was formally designated a foreign terrorist organization pursuant to 8 U.S.C. § 1189, see § 2339B(a) and (g)(6); and so a prohibited donation in the wake of that designation would be prima facie proof of one’s intent to further terrorism.7 The same could be said of donations to zakat committees and other organizations that themselves have been formally designated as terrorist organizations based on their links with Hamas. On the other hand, a factfinder confronted with evidence that a donor gave only to a non-designated, Hamas-controlled hospital for the purpose of funding the medical services provided by that hospital would be free to conclude that the donor had a benign intent and did not aid or abet Hamas’s terrorism even if, in the abstract, one might believe that furthering Hamas’s humanitarian activity enhances its image and thereby supports its violent activities. The ability of the factfinder to draw such distinctions is important, given the difficulty there might be in deciding, under the majority’s standard, what constitutes a terrorist organization and what constitutes the knowing provision of support to such an organization. Organizations that openly embrace terrorism as their declared goal are easy to categorize as terrorist organizations. But what about organizations that engage in terrorism but disclaim responsibility? Or organizations whose members frequently engage in terrorist acts with implicit but not explicit approval from the organizations themselves? And what are we to make of charitable entities that are affiliated with such organizations? *713Or charitable entities that receive some but not all of their funding from such organizations — a hospital that receives contributions from Hamas but is not controlled by it, for example? I am not sure just how far the majority’s liability rule extends. Insisting on proof of a donor’s intent to support terrorism would help to confirm the donor’s culpability in instances where the terrorist nature of the organization receiving aid is less clear than it would be if a donor were making out a check payable to Hamas. It would also serve as a principled way to exempt organizations like the Red Cross and Doctors Without Borders, who engage in humanitarian work that may incidentally or tangentially aid individual terrorists or terrorist organizations, but who have no intent to aid terrorist activity.
The intent requirement would also play a vital role in protecting the First Amendment rights of those accused of facilitating Hamas’s terrorism. The possibility that a section 2333(a) suit might implicate First Amendment rights is not an abstract one. Even to the extent that such a suit is based on the money that a defendant has contributed to an organization that engages in terrorism, the defendant’s First Amendment rights must be accounted for, given that donating money to an organization, though it is not speech in and of itself, is one way to express affinity with that organization and to help give voice to the viewpoints that organization espouses. See Buckley v. Valeo, 424 U.S. 1, 65-66, 96 S.Ct. 612, 657, 46 L.Ed.2d 659 (1976) (per curiam) (“The right to join together ‘for the advancement of beliefs and ideas’ is diluted if it does not include the right to pool money through contributions, for funds are often essential if ‘advocacy’ is to be truly or optimally ‘effective.’ ”) (quoting NAACP v. Alabama, 357 U.S. 449, 460, 78 S.Ct. 1163, 1170, 2 L.Ed.2d 1488 (1958)); see also Citizens Against Rent Control v. Berkeley, 454 U.S. 290, 102 S.Ct. 434, 70 L.Ed.2d 492 (1981). Certainly, given the government’s paramount interest in battling terrorism, the government may prospectively ban, and even criminalize, donations to an organization that it deems a terrorist organization. See § 2339B(a); Boim I, 291 F.3d at 1027; Humanitarian Law Project v. Reno, 205 F.3d 1130, 1135 (9th Cir.2000). Hamas was so designated in 1997, the year after David Boim was murdered. See n. 7, supra. But when an organization engages in both legal and illegal activities and donations to that organization have not been prohibited, a donor may not be held civilly liable for the organization’s illegal activity based solely on his contributions, for to do so would infringe upon the defendant’s First Amendment freedoms. In re Asbestos School Litigation, 46 F.3d 1284, 1290 (3d Cir.1994) (Alito, J.).
And money is not the only type of support that the defendants are alleged to have provided Hamas. One need only look again at the conduct for which AMS was held liable by the district court: hosting Hamas speakers at its conferences, publishing pro-Hamas articles and editorials in his newsletters, rallying support for HLF when it was declared a terrorist organization, and so forth. 340 F.Supp.2d at 908-13. All of that conduct involves pure speech. See ante at 700; Boim I, 291 F.3d at 1026.
And so the First Amendment is very much implicated by this case. Both through their contributions of money to Hamas and its subsidiary organizations, and (in the case of AMS) through their advocacy on behalf of Hamas, the defendants have demonstrated an affiliation with and affinity for Hamas. But NAACP v. Claiborne Hardware Co., 458 U.S. 886, 102 S.Ct. 3409, 73 L.Ed.2d 1215 (1982), holds that an individual may not be held *714civilly liable for his mere association with an organization whose members engage in illegal acts.
Civil liability may not be imposed merely because an individual belonged to a group, some members of which committed acts of violence. For liability to be imposed by reason of association alone, it is necessary to establish that the group itself possessed unlawful goals and that the individual held a specific intent to further those illegal aims.
Id. at 920, 102 S.Ct. at 3429 (footnote omitted). Moreover, an individual’s intent vis-a-vis an organization that holds both lawful and unlawful purposes “must be judged ‘according to the strictest law,’ ”
for “otherwise there is a danger that one in sympathy with the legitimate aims of such an organization, but not specifically intending to accomplish them by resort to violence, might be punished for his adherence to lawful and constitutionally protected purposes, because of other and unprotected purposes which he does not necessarily share.”
Id. at 919, 102 S.Ct. at 3429 (quoting Noto v. United States, 367 U.S. 290, 299-300, 81 S.Ct. 1517, 1521, 6 L.Ed.2d 836 (1961)). The panel in Boim I recognized that the aiding and abetting standard is consistent with the rule announced in Claiborne Hardware in that it conditions liability on proof that a defendant knew of the organization’s illegal purposes and had the intent to further those purposes when that defendant joined and/or aided the organization. 291 F.3d at 1023-24. By contrast, the majority’s approach requires no proof of an intent to further Hamas’s activities; so long as a donor to Hamas or its affiliate knows that Hamas engages in terrorism, the donor is liable for any terrorist act committed by Hamas against an American citizen regardless of the purpose behind the donation.
The majority suggests that the rule of Claiborne Hardware does not apply because violence is a stated goal of Hamas rather than something a few rogue members happen to engage in without its approval.
The defendants in the present case could not be held liable for acts of violence by members of Hamas that were not authorized by Hamas.... But as Hamas engages in violence as a declared goal of the organization, anyone who provides material support to it, knowing the organization’s character, is punishable ... whether or not he approves of violence.
Ante at 700 (emphasis in original). But this holding is directly contrary to Claiborne Hardware, which requires proof of a defendant’s intent to further violence even when violence is a goal that the organization embraces. See 458 U.S. at 920, 102 S.Ct. at 3429 (“For liability to be imposed by reason of association alone, it is necessary to establish that the group itself possessed unlawful goals and that the individual held a specific intent to further those illegal aims.”) (emphasis added). See Scales v. United States, 367 U.S. 203, 229, 81 S.Ct. 1469, 1486, 6 L.Ed.2d 782 (1961) (individual may be convicted for active membership in organization that advocates violent overthrow of U.S. government so long as there is “clear proof that a defendant ‘specifically intend[s] to accomplish [the aims of the organization] by resort to violence.’ ”) (quoting Noto v. United States, 367 U.S. at 299, 81 S.Ct. at 1522); see also Communist Party of Indiana v. Whitcomb, 414 U.S. 441, 447-49, 94 S.Ct. 656, 661-62, 38 L.Ed.2d 635 (1974) (government may not forbid advocacy of lawbreaking or use of force unless it is inciting imminent lawless action) (citing Brandenburg v. Ohio, 395 U.S. 444, 447-48, 89 S.Ct. 1827, 1829-30, 23 L.Ed.2d 430 (1969)); Elfbrandt v. Russell, 384 U.S. 11, 15-18, 86 *715S.Ct. 1238, 1240-41, 16 L.Ed.2d 321 (1966). Certainly I agree that someone who gives money or other support to Hamas knowing that it will be used for terrorist activity — a violation of section 2339A(a) — can be held civilly liable for that activity, but in that case one’s intent could readily be inferred. But to impose liability based on aid that may have been given — and, in fact, used-for humanitarian purposes is to do exactly what Claiborne Hardware proscribes: punish the supporter “for his adherence to [an organization’s] lawful and constitutionally protected purposes, because of other and unprotected purposes which he does not necessarily share.” 458 U.S. at 919, 102 S.Ct. at 3429 (quoting Noto).
Given that the majority’s analysis requires no proof of that any of the defendants intended to support Hamas’s terrorism, it is inconsistent with the Supreme Court’s First Amendment jurisprudence. Although the majority suggests that an intent requirement would, as a practical matter, eliminate donor liability except in those few cases where a donor declared his intent to support terrorism, ante at 698, that certainly is not true in other areas of the law where proof of a defendant’s intent is required. As we often note in employment discrimination and a wide variety of other cases, there is rarely direct proof of a defendant’s intent, and yet intent can be proved circumstantially. See, e.g., Reeves v. Sanderson Plumbing Prods., Inc., 530 U.S. 133, 141, 120 S.Ct. 2097, 2105, 147 L.Ed.2d 105 (2000) (age discrimination); Amrhein v. Health Care Serv. Corp., 546 F.3d 854, 858 (7th Cir.2008) (Title VII retaliation); United States v. Roberts, 534 F.3d 560, 571 (7th Cir.2008) (wire fraud); United States v. Patterson, 348 F.3d 218, 225-26 (7th Cir.2003) (narcotics conspiracy), abrogated on other grounds by Blakely v. Washington, 542 U.S. 296, 124 S.Ct. 2531, 159 L.Ed.2d 403 (2004); Toushin v. Comm’r of Internal Revenue, 223 F.3d 642, 647 (7th Cir.2000) (tax fraud); United States v. Rose, 12 F.3d 1414, 1417, 1420 (7th Cir.1994) (aiding and abetting the transportation and receipt of a stolen motor vehicle). Moreover, should there be evidence that a defendant has made statements in support of the use of violence to achieve political ends, relying on such statements as proof that the defendant provided financial or other aid to a terrorist organization with the intent to support its terrorist activities would not, as the majority suggests, ante at 698-99, pose a First Amendment problem. See Wisconsin v. Mitchell, 508 U.S. 476, 489, 113 S.Ct. 2194, 2201, 124 L.Ed.2d 436 (1993) (“The First Amendment ... does not prohibit the evidentiary use of speech to establish the elements of a crime or to prove motive or intent.”).
5.
Finally, the majority treats Dr. Paz’s affidavit as sufficient evidence that Hamas was responsible for David Boim’s murder. Although the majority recognizes that Paz relied on a variety of unauthenticated electronic and documentary sources for his conclusion, it nonetheless deems his affidavit admissible and sufficient to sustain summary judgment for the plaintiffs on this point because an expert is free in forming his opinion to rely on evidence that would not be admissible in court. Ante at 704. But the panel’s principal point was that Dr. Paz’s conclusion as to who killed David Boim is meaningless without reference to the websites and documents that he so heavily relied upon in forming his opinion, and yet allowing Paz to recount what those sources say without establishing their authenticity and trustworthiness would contradict the basic requirement that expert opinion have “a reliable foundation,” Daubert v. Merrell Dow Pharmaceuticals, supra, 509 U.S. at 597, *716113 S.Ct. at 2799; see also Fed.R.Evid. 703. Paz’s opinion is based exclusively on what these websites and documents say; he has no personal knowledge of who killed David Boim. So if these sources are not genuine or say something other than what he has represented, then his opinion is worthless. No expert worth his salt would base his opinion on internet and documentary sources without assuring himself that they are reliable — that a website thought to be a Hamas site is, in fact, a website controlled by Hamas and authorized to make representations on its behalf, for example, or that what purports to be the written judgment of a foreign tribunal is actually that. But Paz’s affidavit does not describe any such efforts that he made, and there is no other evidence in the record that establishes the authenticity and reliability of the websites and documents whose contents he recounts.
The glaring lack of any information confirming the authenticity and accuracy of Paz’s sources raises obvious doubts about the reliability of his opinion. To cite just a few examples: For the proposition that Hinawi killed David Boim, Paz relies on a document in Arabic that purports to be the written judgment reflecting Hinawi’s conviction and sentence before a Palestinian Authority tribunal, along with the notes of a U.S. State Department employee who observed Hinawi’s trial. Here is the cover letter accompanying and describing both the trial notes and the judgment (Figure 1), followed by the judgment form (Figure 2):
Figure 1: Cover letter
[[Image here]]
*717Figure 2: Hinawi Judgment
[[Image here]]
No translation of the Arabic-language judgment has been provided (it could be an advertisement for all I know), and neither the judgment nor the notes of the foreign service officer have been authenticated in any meaningful way by the cover letter, which does not even identify the letter’s author. We have absolutely no way to know, given the current state of the record, whether these documents are what Paz says they are, and thus no way of assessing the reliability of his conclusions. As a final example, here is one of the web pages Paz relied on as evidence that Ha-mas took responsibility for David Boim’s murder:
*718Figure 3: web page
[[Image here]]
The selective translation obviously makes it impossible for the reader to independently evaluate the context and meaning of what Paz is relying on. Notwithstanding these infirmities, the majority is content not only to deem Paz’s opinion admissible, but to sustain the entry of summary judgment against the defendants on this point. The defendants cannot be faulted for failing to refute Paz’s conclusions, see ante at 704-05, for the party opposing summary judgment is not required to rebut factual propositions on which the movant bears the burden of proof and that the movant has not properly supported in the first instance. See Celotex Corp. v. Catrett, 477 U.S. 317, 331, 106 S.Ct. 2548, 2557, 91 L.Ed.2d 265 (1986) (Brennan, J., dissenting) (citing 10A C. Wright, A. Miller, & M. Kane, Federal Practice & Procedure § 2727 (2d ed.1983)); L & W, Inc. v. Shertech, Inc., 471 F.3d 1311, 1318 (Fed.Cir.2006); Black v. M & W Gear Co., 269 F.3d 1220, 1238 (10th Cir.2001). In any other sort of case, this sort of sloppiness would not be tolerated, and we certainly would not sustain the entry of summary judgment based on such shaky evidence.8
6.
The murder of David Boim was an unspeakably brutal and senseless act, and I can only imagine the pain it has caused his parents. Terrorism is a scourge, but it is our responsibility to ask whether it presents so unique a threat as to justify the abandonment of such time-honored tort requirements as causation. Our own re*719sponse to a threat can sometimes pose as much of a threat to our civil liberties and the rule of law as the threat itself. See, e.g., Korematsu v. United States, 323 U.S. 214, 65 S.Ct. 193, 89 L.Ed. 194 (1944). The panel’s opinion in Boim II took a conservative approach, fully consistent with precedent, that insisted on proof that the defendant’s actions were a cause of Hamas’s terrorism, proof that the defendants intended to support terrorism, and admissible evidence to support such basic factual points as whether Hamas was responsible for David Boim’s murder. This en banc court, by contrast, relieves the plaintiffs of all of these obligations, following a path that portends sweeping liability for those individuals and groups who give their support to the humanitarian activities and affiliates of terrorist organizations but who may have no intent to support terrorism and whose actual link to terrorism has never been evaluated by a factfinder. I stand by the approach taken by the Boim I and Boim II panel.
7.
For all of the reasons set forth above and in the panel’s Boim II opinion, I would remand for further proceedings as to all four defendants, including Salah. I would require the plaintiffs on remand to demonstrate that any financial or other support the defendants have given to Hamas and Hamas-affiliated entities was in some way a cause of Hamas’s terrorism. I would also insist the plaintiffs set forth a more complete evidentiary foundation for the proposition that Hamas killed David Boim.
. Judge Wood also joins this opinion except as to Salah’s liability.
. Judge Evans, in his dissent from this holding, not only thought that the plaintiffs could show causation, but that they already had. 511 F.3d at 760-61.
. HLF's ties to Hamas have yet to be evaluated in this litigation, because the district court erroneously gave collateral estoppel effect to the D.C. Circuit’s determination that HLF funded terrorism by funding Hamas and its affiliates. See ante at 700-01; Boim II, 511 F.3d at 726-33.
. Thus, when I discuss aid given to zakat committees and other organizations controlled by or affiliated with Hamas, I am assuming that they are not, in fact, mere fronts for Hamas that are used to launder donations meant to fund Hamas's terrorism.
. There is a point in the majority’s opinion at which it appears to describe its liability framework as one that straddles both primary and secondary liability. After concluding that Congress did not authorize the imposition of secondary liability under section 2333(a), ante at 688-90, the majority goes on to say that "there is no impropriety in discussing” such secondary liability theories as conspiracy and aiding and abetting, ante at 691, and that "[pjrimary liability in the form of material support to terrorism has the character of secondary liability,” ante at 691. I must confess to some uncertainty as to the majority's meaning. What is clear to me is that the majority has rejected the theories of secondary liability discussed in Boim I and Boim II, and at the same time the majority is not conditioning liability under section 2333(a) on proof of a defendant’s intent or agreement to aid terrorism, which would of course be necessary to recover under a traditional aiding and abetting or conspiracy theory of liability. I shall therefore describe the majority’s liability framework as one of primary liability while recognizing that the majority sees some continued relevance — I am not sure what — in aiding and abetting and conspiracy concepts to liability under section 2333.
. True, “medicine” is excluded from the definition of the “material support or resources” to terrorists proscribed by section 2339(A)(a), see ante at 699, citing § 2239(A)(b)(l). But to the extent that the medical exclusion lets an organization like the Red Cross off the hook (although I note that the services of the Red Cross are not limited to medical aid), then it logically ought to exonerate those who fund medical services provided by Hamas hospi*711tals, for example, for the statute in no way suggests that the exclusion depends on how the medical aid is provided. Yet the majority insists that funding a Hamas hospital would render the donor liable while directly aiding individual Hamas terrorists would not. See ante at 698, 699.
. Hamas previously had been designated a terrorist organization in January 1995 (some fourteen months before David Boim was killed) and donations to Hamas were prohibited from that point forward. See Boim II, 511 F.3d at 720. But the criminal penalties of section 2339B were not triggered until 1997 (the year after Boim was murdered), when Hamas was designated a foreign terrorist organization pursuant to section 1189. See Boim I, 291 F.3d at 1016.
. One of the other concerns the panel noted was the lack of a foundation for attributing the representations on various websites regarding David Boim’s murder to Hamas. 511 F.3d at 753. If that seems like nitpicking, consider the following: Octavia Nasr, "bin Laden hacked?”, AC360, http://ac360. blogs.cnn.com/2008/10/23Ain-laden-hacked/ (last visited 11/25/2008).