The Learned Intermediary Doctrine: Debunking Myths

The learned intermediary doctrine is not sexy.  Its application doesn’t require depositions or a jury trial.  Look no further than its name:  it’s a legal doctrine.  Nevertheless, drug and device manufacturers still face a litany of ruses from plaintiff lawyers misconstruing the doctrine.  And some courts seem all too willing to entertain them.

Local-rule page limits often leave drug and device defendants without the space to engage the underpinnings of plaintiff-lawyer misdirection on the learned intermediary doctrine.  Here we have that space.  No, the learned intermediary doctrine is not a “defense.”  Its application doesn’t depend on the cart-before-the-horse argument that “the manufacturer must first prove that its warnings were adequate.”  And it doesn’t go away just because the complaint’s causes of action didn’t include the title “failure to warn.”

The Learned Intermediary Doctrine Is Not a Defense

Some plaintiff lawyers love calling the learned intermediary doctrine a defense.  They release this philosophical balloon—without explaining what it means—to impose an affirmative-defense-level burden on defendants relying on a simple doctrine.  The resulting mistaken implication is that the defendant needs to prove something for the doctrine to “apply.”

This refrain is cobbled together from a glut of irrelevant case law that has seeped into drug and device cases, but it belies the fact that the learned intermediary doctrine is just that—a doctrine.  It is a definition of duty, nothing else.  And we should not forget that it is “[j]udges, not juries, [who] ordinarily determine whether a duty exists and the standard it imposes.”[1]

The doctrine exists in prescription-drug and -device cases because it defines duty: “The obligation of a manufacturer to warn about risks attendant to the use of drugs and medical devices that may be sold only pursuant to a health-care provider’s prescription traditionally has required warnings directed to health-care providers and not to patients.”[2]  Despite the Third Restatement’s clear prescription that the doctrine defines to whom a duty to warn flows, the idea that the learned intermediary doctrine is some fact-intensive defense has its footing in case law that has no place in the drug and device context.

Trapped in Irrelevant Precedent

Take my home state’s convoluted explanation of the doctrine as a perfect example of how it can be muddled.  Follow along.

In 2014, the Sixth Circuit, construing Tennessee law in a pharmaceutical case, wrote that “the [learned] intermediary doctrine constitutes a defense by pharmaceutical manufacturers in cases where plaintiff has suffered injury from a medication prescribed by a doctor.”[3]  It quoted a Tennessee Supreme Court opinion from a case involving—like many other states’ learned intermediary doctrine caselaw—a seller of asbestos.[4]  In that asbestos case, the Tennessee Supreme Court cited an actual pharmaceutical case from 1994, Pittman v. Upjohn, about the maker of a diabetes drug.[5]  Pittman, which established the learned intermediary doctrine at the highest level in Tennessee, cited an explosion case involving the chemical naphtha,[6] as well as the true culprit of it all—comment n to section 388 of the Second Restatement.

Comment n, like the rest of the Second Restatement, was published in 1965.  Though titled “[w]arnings given to a third person,” it makes no mention of drugs or devices, which are extensively regulated by the FDA and sold only to healthcare providers.  Instead, comment n speaks in terms of “chattels . . . often supplied for the use of others,” “contractor[s] furnish[ing] the scaffoldings or other appliances which his subcontractor and the latter’s servants are to use,” and “when an automobile is lent for the borrower to use for the conveyance of his family and friends.”[7]

Finding the Way Out

It is true, as the drafters write, that “[a]ll sorts of chattels may be supplied for the use of others, through all sorts of third persons and under an infinite variety of circumstances.”[8]  And in each individual circumstance of supplying chattels to others, it might be reasonable to assess who those “third persons” are and whether they might pass along a warning.  In those circumstances (say, in an asbestos case), you might call the learned intermediary doctrine a defense:  the manufacturer needs to make some showing that the layperson intermediary it relied upon has the credentials or knowledge to be trusted to pass along a warning.

But those factual questions ask whether the third person is a sophisticated user, not whether it is a learned intermediary.  So, for example, when the California Supreme Court sought to examine “how the sophisticated intermediary doctrine applies in California” in a case involving (you guessed it—asbestos!), it noted that California had already “adopted the learned intermediary doctrine, a related rule that applies when drugs or medical devices are supplied in the context of the doctor-patient relationship.”[9]

Of course, sorting out duties among the infinite links in the asbestos supply chain is not a good comparator for prescription drugs and medical devices.  The latter products are only supplied—by law—to healthcare providers.  And those healthcare providers are tasked with determining whether the drug or device is appropriate for the patient in the first instance, as well as which warnings should be passed along to the patient, and how to convey risks and benefits.  Because the sophistication of the provider is built into the equation, there is no need in a drug or device case for a jury to decide any facts about whether “one supplying a chattel for the use of others through a third person has satisfied his duty to those who are to use the chattel by informing the third person of the dangerous character of the chattel.”[10]

By federal regulation, prescription medical devices are “not safe” unless they are administered “under the supervision of a practitioner licensed by law to direct the use of such device[s].”[11]  And because practitioners licensed by law are the only ones actually administering medical devices, the device manufacturers need not warn of risks “commonly known to practitioners licensed by law to use the device[s].”[12]  Prescription drugs are the same.  They are not for sale to the consuming public, and they are subject to extensive labeling requirements directed to the physicians who prescribe them.[13]

Federal regulation isn’t the end of the story.  State law already imposes duties on the intermediaries who prescribe drugs and devices.[14]  Indeed, we entrust the states with licensing those people to practice medicine, which includes prescribing drugs and devices.  They’re called physicians.  For those reasons, “while the manufacturer of a medical device has a duty to warn a patient’s physician of the risks associated with the device, the manufacturer is not responsible for how the physician uses the device and renders the medical care.”[15] 

When courts must rely on two pages of briefing that quote random learned intermediary precedent, they can struggle to understand the uniqueness of the drug and device context.  When they actually grapple with the history of the doctrine, they recognize the plaintiff-lawyer ruse and reject the argument that a defendant need prove something in order for the doctrine to apply:  “[W]ithin the prescription drug context, the learned intermediary doctrine is more akin to a common-law rule rather than an affirmative defense.”[16]  And thus, “[i]n the context of prescription drugs or medical devices, the learned intermediary doctrine is still applied as a matter of law.”[17]

The Learned Intermediary Doctrine Does Not Depend on the Adequacy of Warnings

The same “defense” fallacy is the foundation of another learned intermediary smokescreen—that the doctrine only “applies” if the drug or device manufacturer provided an adequate warning.

While the caselaw in nearly every state is riddled with this misconception, at its core, it innocently misstates an obvious proposition—that if the manufacturer did not adequately warn the physician, judgment cannot automatically be rendered in the manufacturer’s favor.  In other words, the precedent rightly recognizes that the learned intermediary doctrine is not some complete bar to liability in the first place.

For this reason, manufacturers should never argue that the learned intermediary doctrine is an escape from liability; it is instead protection against an unfounded duty to warn patients directly.  It should only be argued as a “bar” to liability when the plaintiff’s case rests solely on the imposition of a duty to warn the plaintiff himself, rather than the plaintiff’s healthcare provider.

When treated as a doctrine rather than some complete “bar” to liability, courts can differentiate the misguided case law suggesting that manufacturers must prove they adequately warned before the doctrine can “apply”:

[T]his authority is incorrect to the extent that it suggests that the learned intermediary doctrine has no effect where plaintiffs allege that warnings are inadequate.  The learned intermediary doctrine simply provides that the prescribing doctor in reality stands in the shoes of the ordinary consumer to receive a manufacturer’s warnings.


Accordingly, here the Court concludes that even when a plaintiff proves that warnings were inadequate, the learned intermediary doctrine still applies.  A plaintiff must prove that inadequate warnings altered the prescribing physician’s decision to prescribe.[18]

Indeed, in the drug and device context, what does it even mean that the learned intermediary doctrine only applies if the warning is adequate?  What happens if it was not adequate?  Does an incomplete warning mean that the manufacturer’s duty somehow shifts from the trained physician to the unknowing patient?  At trial, is the prescribing physician’s testimony now completely irrelevant because the doctrine doesn’t “apply”?

Of course not. The case law simply intends that the learned intermediary doctrine does not bar a cause of action if the warning is inadequate.  If the warning is not adequate as a matter of law, the trial is still about the content of the manufacturer’s warning to the physician, and the jury would decide whether that warning was adequate and whether proximate cause exists based on the physician’s testimony.

The Learned Intermediary Doctrine Is Not Claim Specific

A final ambush of the learned intermediary doctrine is wholly lawyer-driven.  If the doctrine applies to claims titled “failure to warn,” why not just call plaintiff’s failure-to-warn claim something else?  Breach of express warranty, implied warranty, negligence, negligent misrepresentation, fraud, or even your favorite consumer-protection statute—why not?

But if the learned intermediary doctrine is a real rule defining duty, then the object of a manufacturer’s duty remains the same no matter what cause of action is brought:  “If the doctrine could be avoided by casting what is essentially a failure to warn claim under a different cause of action such as a violation of the [state law consumer protection act] or a claim for misrepresentation, then the doctrine would be rendered meaningless.”[19]  Thus, no matter whether a plaintiff claims that the manufacturer:

  • breached an express warranty by omitting a warning,
  • sold an unmerchantable product because it omitted a warning for that product,
  • negligently or fraudulently misrepresented by omitting a warning,
  • negligently or fraudulently concealed risks from its warnings, or
  • engaged in a deceptive trade practice by omitting a warning…

it’s all the same as a matter of common sense and under the learned intermediary doctrine.  Changing the name of a cause of action cannot shift the law’s prescription of whom is owed a duty.


The learned intermediary doctrine is foundational to prescription drug and device cases. Perhaps because of that, some plaintiff lawyers seek to undercut it at every turn.  The best way to steer a judge in the right direction is to explain the tracks on which the doctrine was laid and illustrate how the attempts to derail a doctrine defining duty have gone off track.

[1] Dobbs’ Law of Torts § 125.

[2] Restatement (Third) of Torts: Products Liability § 6 cmt. b (emphasis added).

[3] Payne v. Novartis Pharms. Corp., 767 F.3d 526, 530 (6th Cir. 2014) (quoting Nye v. Bayer Cropscience, Inc., 374 S.W.3d 686, 701 (Tenn. 2011).

[4] Nye v. Bayer Cropscience, Inc., 347 S.W.3d 686, 700–01 (Tenn. 2011).

[5] Pittman v. Upjohn Co., 890 S.W.2d 425, 429–30 (Tenn. 1994).

[6] Whitehead v. Dycho Co., 775 S.W.2d 593, 596–07 (Tenn. 1989).

[7] Restatment (Second) of Torts § 388 cmt. n.

[8] Id.

[9] Webb v. Special Electric Co., 370 P.3d 1022, 1034 n.10 (Cal. 2016) (emphasis added) (citing Carlin v. Superior Court, 920 P.2d 1347, 1354 (Cal. 1996)).

[10] Restatment (Second) of Torts § 388 cmt. n.

[11] 21 C.F.R. § 801.109.

[12] Id.

[13] See, e.g., 21 C.F.R. § 201.57.

[14] See, e.g., N.Y. Pub. Health Law § 2805-d(1) (“Lack of informed consent means the failure . . . to disclose to the patient such alternatives thereto and the reasonably foreseeable risks and benefits involved as a reasonable . . . practitioner under similar circumstances would have disclosed, in a manner permitting the patient to make a knowledgeable evaluation.”); Flores v. Liu, 60 Cal. App. 5th 278, 292–93 (2021) (“Because a patient relies upon her physician’s greater medical knowledge when seeking medical treatment, the physician has a fiduciary-like duty to obtain his patient’s informed consent regarding which course of treatment to pursue.”);

[15] Greenwood v. Tehrani, 2017 N.Y. Slip Op. 31963, at *3 (N.Y Sup. Ct. Sept. 15, 2017).

[16] Centocor, Inc. v. Hamilton, 372 S.W.3d 140, 164 (Tex. 2012).

[17] See, e.g., Pringle v. Johnson & Johnson, No. 13-81022-CIV, 2020 WL 4501834, at *4 (S.D. Fla. Jan. 30, 2020).

[18] Shahbaz v. Johnson & Johnson, No. CV 13-07382, 2020 WL 5894590, at *13–14 (C.D. Cal. July 31, 2020) (internal citations omitted) [cleaned up].

[19] In re Norplant Contraceptive Prods. Liab. Litig., 955 F. Supp. 700, 709 (E.D. Tex. 1997), aff’d sub nom. In re Norplant Contraceptive Prods. Litig., 165 F. 3d 374 (5th Cir. 1999).