Airplane taking off from the airport.

In-Flight COVID Transmission: Surveying the Liability Landscape

By Christopher Robertson

Do airlines have legal obligations to manage the risk of in-flight infections?

In the pre-COVID era, I answered this question affirmatively. In a 2016 paper, I reviewed the scientific literature showing that airline travel is a key vector for spreading infectious disease, both because airports and airplanes tend to mix people in such close quarters that they are likely to infect each other, and because it efficiently distributes infected people around the world to then infect more people.

Indeed, prior research demonstrated that airline travel was a key mechanism for spread of seasonal flu virus (which could be studied, due to the natural experiment of the September 11 attack stopping airline travel). Moreover, studies had documented person-to-person spread of SARS, influenza, and smallpox among people sitting near each other on airline flights.

Given the foreseeability of the risk, I argued that airlines’ obligations to prevent infections from passengers arise both under federal statutes and regulations and under common law tort duties of care. To be sure, federal law allows airlines to refuse boarding to passengers who “the carrier decides is, or might be, inimical to safety.” In Adamsons v. Am. Airlines, Inc, the New York Supreme Court held that the airline permissibly acted under federal law to refuse passage to an individual in extreme pain due to undiagnosed, mysterious illness.

And tort law duties may make that permissive power obligatory, to protect passengers. Under common law of torts, the general duty of reasonable care (negligence) may apply. Or, more traditional courts may invoke the heightened standards of common carrier doctrine, as the Louisiana Supreme Court did in Green v. Taca Int’l Airlines (1974), describing the duty as, “‘the highest standard of care,’ ‘highest degree of vigilance, care and precaution for the safety of those it undertakes to transport,’ or ‘the strictest diligence.’”

Because of airlines’ legal obligations to mitigate the risk of in-flight infectious disease transmission, in 2016 I suggested that they could require vaccination, where safe and effective vaccines were widely available. Thus, even before special COVID-19 emergency declarations and legislation, I argued that federal agencies already had the authority to regulate these risks by requiring passengers to be vaccinated.

However, no such requirements materialized during the COVID-19 pandemic. Even when the federal government famously required workers to be vaccinated (until the Supreme Court said nope), and the federal government required incoming international travelers to be vaccinated, it only required domestic passengers to wear masks (until a federal judge in Florida also said nope). And that mask mandate (when it was in force), did not require high-quality masks, such as N95 respirators, nor did it require domestic travelers to be vaccinated or present a negative test.

Although airlines could themselves have required passengers to be vaccinated, tested, and/or wear high-quality masks on some or all of their flights, American air carriers did not do so. Undoubtedly, some passengers were infected as a result, and either they or third parties suffered accordingly.

With a research assistant, I looked for torts cases against airlines, primarily by passenger plaintiffs, claiming that the airlines failed to take reasonable precautions against the spread of COVID-19 by their passengers. In addition to the cases of employees challenging vaccine mandates, we predictably found some passenger cases involving breach of contract, alleging that airlines failed to refund fees for cancelled or delayed flights. Nonetheless, for our key interest of a passenger COVID infection acquired in-flight, we came up with nothing, nada, zilch — not a single torts case fitting this fact pattern. Despite there being a compelling legal argument for airlines to mitigate the risk of contracting an infectious disease in-flight, and despite the lack of precautions enacted, torts suits against airlines have not materialized.

The closest we came was a case involving a flight attendant, Est. of Madden v. Sw. Airlines, Co. Carol Madden was an employee flight attendant who sued Southwest Airlines Co. asserting four negligence-based causes of action related to her deceased husband’s contraction of COVID-19 from her, leading to his subsequent death. As a Southwest flight attendant, Ms. Madden was required to attend a training program, where “Southwest allegedly failed to implement reasonable safety and health protocols to prevent the participant flight attendants from contracting or spreading COVID-19.” Specifically, the plaintiff alleged that Southwest should have screened participants and instructors for COVID-19, and excluded those who were positive. Moreover, Madden argued that Southwest should be liable for allegedly “failing to enforce mask policies that would have lessened transmission, failing to implement safe distancing requirements… and failing to implement contact tracing that would have prevented transmission after-the-fact or alerted participant flight attendants at an early time to COVID-19 exposure.”

In Madden, the district court noted that, “on the facts as presently alleged, such an outcome is both foreseeable and not unreasonably remote.” Further, the court held that “finding a duty here would incentivize employers to take minimum precautions against the spread of COVID-19 to employees and their families via the implementation of minimum safety procedures, [and] it would appear uncontroversial to suggest that stopping the spread of COVID-19 is an important policy goal, and the existence of a duty would unmistakably further that goal by preventing first order infections of employees and therefore protecting against later spread to third parties.”

The court nonetheless dismissed the claim, holding that the airline had no duty to their employee’s spouse: “Maryland courts have made their priorities with regard to third-party duties clear, and the prospect of an unstemmed and ill-defined tide of third-party plaintiffs bringing suit predominates the duty analysis.” In recent decades, courts have been wrestling with a similar question in “secondary exposure” cases to asbestos, where employees bring home the fibers on their clothes. In those cases, courts have been split, with several finding duties of care to foreseeable third parties. In any case, while finding no duty to third parties (here the spouse), the Madden holding would not be a bar to many other sorts of cases where the plaintiff was directly infected by the airline’s negligence.

So why are we finding no passenger COVID cases? One possibility is that, because the United States did not develop a robust contract-tracing mechanism, patients have no real way to determine, much less plausibly allege in a complaint, that the cause of their COVID infection was in fact their airline travel. This problem has arisen in similar cases involving infectious diseases on cruise ships. However, there is some empirical evidence to support in-flight COVID transmission: a June 2021 article summarized seven airline flights in which COVID-19 infections were known to have occurred. And a simulation study suggested that if airlines had required patients to present a negative COVID-19 test as a condition of flying, infections among travelers could have been reduced by more than 30%. Another simulation study found that the risk of the pandemic spreading to New Zealand could be dramatically reduced if airlines implemented “a pre-flight PCR test of saliva, three subsequent PCR tests … and various other interventions (mask use and contact tracing).”

The U.S. air travel industry could have separated at either the airline or individual flight level, allowing passengers to choose whether they wished to travel with other vaccinated, tested, and masked passengers, or not. Unfortunately, not a single airline stepped forward to offer a COVID-safer alternative. This is another fact working in favor of U.S. airlines — they all seem to take roughly the same precautions, which makes it harder to allege a breach of the duty of care.

Further, although a company’s compliance with regulatory standards does not establish the duty of care, juries may well tend to think it unfair to ding a company when they were “following the rules” established by federal agencies. In this sense, the regulatory floor may in practice become a liability ceiling, even if it doesn’t formally preempt state tort law theories.

Ultimately, when we think about tort law as a kind of private-law solution to pandemic problems, we see that is a fairly weak tool. There is no substitute for strong regulatory action to protect people from common threats to their health and safety.

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