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  • Writer's pictureAlison McManus

Was the Invention of Agent Orange an Invention at All?

Updated: Apr 26, 2023

Agent Orange is older than you might think. Although the herbicide is rightfully associated with the U.S. military’s defoliation campaigns in Cold War era Vietnam, it first emerged twenty years earlier during a much different global conflict. The chemical cocktail’s two active ingredients were synthesized and studied extensively in the early 1940s, as British, Canadian, and American chemists investigated novel herbicides for purposes both militant and peaceful: crop destruction, tactical defoliation, lawn maintenance, and the killing of agricultural weeds. When it came to herbicidal warfare, the original intended target was not Vietnam but rather Germany or Japan.

After the war, American chemical companies fought one another for the right to mass produce the herbicide, filing a series of lawsuits that challenged the concept of chemical invention. In what follows, I focus on one of these intellectual property suits, which pitted the industrial giant Sherwin-Williams (and its government connections) against the relatively modest American Chemical Paint Company, headquartered in Ambler, Pennsylvania. In their litigation, the two companies mobilized competing visions of chemical invention, which held differing accounts of theory versus practice and analogy versus experiment in chemical labor. At stake was a claim to invention, a multimillion-dollar product, and a foundational weapon of 20th-century colonial violence and ideological proxy wars.

The patent at issue claimed a wide variety of herbicidal preparations based on the chlorinated phenoxyacetic acids, their esters, and their salts. These compounds were not themselves new. To the contrary, they were the product of many decades of research on plant growth hormones, which stretched arguably back to Charles Darwin’s work with light stimuli, first published in 1880. In the mid-1920s, plant physiologists working at the University of Utrecht isolated and identified the first known auxin, or plant growth hormone, indole-3-acetic acid. This naturally occurring hormone could aid in root setting and prevent premature abscission (fruit drop), but use too high a concentration, and the chemicals instead caused injury or death.

In the fifteen years that followed, organic chemists produced a litany of synthetic analogs in a process that Celia Kirby has termed a “chemical jamboree.” American chemist Roy Pokorny synthesized two chlorinated phenoxyacetic acids — 2,4-D and 2,4,5-T — and announced his work in a 1941 issue of the Journal of the American Chemical Society. Though Pokorny did not comment on their applications, chemists and agriculturalists nevertheless recognized the compounds’ utility in the regulation of plant growth. The following year, botanists Percy Zimmerman and Albert Hitchcock of the Boyce Thompson Institute (BTI) in New York State identified the compound 2,4-D as a potent auxin “300 times” more powerful than natural plant growth hormones. The same year, John Lontz of the DuPont Corporation took out two patents on chlorinated phenoxyacetic acids. He did not mention their herbicidal applications, although DuPont scientists already used them that way.

The synthetic auxin field was already well populated by 1942, but Franklin Jones of the American Chemical Paint Company hoped to carve his own intellectual property claim out of the crowd. A long-time independent inventor with over one hundred fifty patents to his name, Jones had recently joined American Chemical and convinced his employer to expand research into the herbicide field. The search for more effective herbicides also took on a personal significance for Jones. He later remarked that his children were particularly susceptible to poison ivy, and he therefore sought better means of killing the plant. According to a court affidavit, Jones chose to focus his search on the chlorinated phenoxyacetic acids after visiting a colleague’s greenhouse in February 1942, where he noted that a certain auxin preparation had caused localized injury to tomato specimens. With a bit of olfactory detective work and continued experimentation, Jones developed what he believed to be a novel invention: the first cheap and effective translocated herbicides.

The Jones patent, issued December 11, 1945, was titled “Methods and Compositions for Killing Weeds” and claimed an immense number of herbicidal preparations. Jones defined the compounds of the invention as the halogenated phenoxyacetic acids, plus their corresponding esters and salts. This umbrella term included 2,4-D and 2,4,5-T as well as their octyl esters, which were later combined into Agent Orange. Jones’s patent likewise described a variety of preparations and methods of application: solutions, emulsions, and pastes, each with different carrier substances. A generous interpretation of the patent could easily include over one hundred chemical compounds, to say nothing of their different preparations.

With patent in hand, Jones and American Chemical began marketing a 2,4-D-based herbicide under the tradename Weedone. Other firms followed suit. Sherwin-Williams produced and sold another 2,4-D-based herbicide named “Weed-No-More,” and, in August 1945, agreed to supply the U.S. Navy with 100,000 tons of the herbicide. Production increased substantially in the postwar period. Both Dow Chemical and the DuPont Corporation produced and sold their own 2,4-D herbicides. Other small companies purchased the herbicide from Dow and resold it under an array of descriptive tradenames: Weedeath (Howard Hanson & Company), Root-an-All (The Drumcliff Company), Dandykill (Plant Products Company), and King 2.4.D.Weeder (King Laboratories, Inc.). These herbicides brought in substantial profits. Dow Chemical made $500,000 from 2,4-D herbicides in 1946 alone – the equivalent of 7.1 million today.

Tomato plants sprayed with a 2,4-D solution at the University of Chicago, February 1944. Courtesy of the University of Chicago Special Collections Research Center.

In the spring of 1946, American Chemical threatened to charge the above companies with patent infringement if they continued producing and selling herbicidal preparations covered under the Jones patent. In response, Sherwin-Williams and Dow filed separate lawsuits to declare the Jones patent invalid, believing the U.S. Patent and Trademark Office should never have issued it in the first place.

The Sherwin-Williams vs. American Chemical suit was tried in the Federal District Court of Delaware in 1946–1947. Counsel for Sherwin-Williams advanced a three-part critique of the Jones patent, addressing specificity, novelty, and inventiveness. With regard to specificity, the Plaintiff’s counsel argued that Jones had failed to provide accurate instructions for killing weeds; in an effort to patent the greatest number of compounds, he had inadvertently included several with no appreciable herbicidal activity. Moreover, Jones rarely pinpointed the amount of active ingredient to be used, instead providing a broad range or a minimum value. Given these inconsistencies, a chemical inventor could not reliably reconstruct a weedkiller from the Jones patent alone.

With regard to novelty, counsel for Sherwin-Williams argued that the component parts of the invention already appeared in the patent literature, specifically the aforementioned DuPont patents and a related patent owned by BTI. In their estimation, Jones had merely claimed a new use of an old invention, a practice that U.S. courts explicitly disallowed. Inventors frequently dodged this rule, however, by claiming chemical preparations carefully tailored to differ from examples in the literature, for instance changing a dispersing or emulsifying agent while keeping the active ingredient the same. Jones was no exception, making the argument of complete anticipation a difficult sell in court.

To make the case that Jones had not exercised inventiveness, counsel for Sherwin-Williams relied on a vision of chemical invention that privileged theory over practice and analogical thinking over experiment. They reconstructed Jones’s logic as follows. Prior to patenting 2,4-D and related phenoxyacetic acids, Jones knew that synthetic auxins caused injury and death, and likewise knew that 2,4-D was a powerful auxin. By intuiting that 2,4-D might therefore kill weeds, Jones was merely carrying a simple syllogism to its logical conclusion. “Selecting a known compound to meet known requirements,” the Plaintiff argued, “is not invention.”

In contrast, Jones’s lawyers highlighted the role of practical experiment in chemistry and pushed for intellectual property regimes to reward these elements of chemical labor, too. They argued that opposing counsel engaged in the fallacy of judging an invention by hindsight. Choosing 2,4-D as an herbicide appeared obvious after the fact, but it was by no means a sure bet in 1941. To the contrary, chemists could not easily predict a molecule’s physiological impact under field conditions, even given some knowledge of its potency. To support this non-intuitive claim, Jones’s lawyers introduced an affidavit from Caltech plant physiologist Kenneth Thimann, an expert in auxin research.

Thimann stated that the “potency” of a chemical compound (like that reported by Zimmerman and Hitchcock in 1942) did not reliably translate to toxicity, and patent attorneys should not conflate the two terms. An inventor had to consider other variables, such as solubility and ease of application, or the possibility that a highly potent compound might injure the site of application too quickly, thereby preventing the herbicide from travelling to the roots for a more effective kill. Finding a useful herbicide required practical tinkering, a process of trial and error that logical reasoning alone could not replicate.

In making this argument, Jones’s lawyers identified a broader complication of intellectual property in the chemical sciences. As they later noted, chemistry was “still an experimental science” and “chemical prevision…hardly more possible today than it was in former times.” This meant that certain commonplace practices in patent law, like distinguishing the date of conception from the date of reduction to practice, fit far better with mechanical engineering than the chemical sciences. Even in the 21st century, chemistry retains its dependence on practical experiment, as Hasok Chang observed in a recent edition of Ambix. Reasoning from structure to function – though vastly improved in the last fifty years – remains an imperfect endeavor. In the Jones patent case, attorneys mobilized an essential tension of chemistry to justify their clients’ intellectual property positions. They adjusted the relative weight of logical thinking and practical experiment in their accounts of chemical work, hoping that a judge would take their side.

Ultimately, no judge ruled on the Jones patent. As with so many lawsuits, the 2,4-D litigation ended with a settlement in lieu of a proper ruling. In exchange for a one-time payment of $10,000, American Chemical granted Sherwin-Williams a royalty-free license to produce and sell chlorinated phenoxyacetic acid herbicides. American Chemical also agreed to grant similar licenses to any other firm that requested it. These were unfavorable terms for Jones and his employer, as the cost of the license amounted to only 2% of Dow’s 2,4-D profits in 1946. The terms of the settlement no doubt reflected the multiple weaknesses of Jones’s intellectual property claims, especially its lack of specificity and debatable inventiveness. In this case, appealing to practical experiment failed to justify Jones’s intellectual property claims, though the broader issue of analogy versus practice would remain an open question in chemical patent litigation.

The fall of the Jones patent enabled U.S. chemical conglomerates to cheaply manufacture these herbicides on an industrial scale. In the following years, chlorinated phenoxyacetic acids fulfilled the commercial and military potential that their developers had envisioned, often with disastrous results. These herbicides became ubiquitous in American lawns and multiple arsenals of the Cold War era. The British Royal Air Force deployed them against resistance forces during the Malay Wars of Decolonization (1948–1960), and more famously, the American military sprayed these chemicals over forests and cropland in Vietnam and Cambodia (1962–1971). At the root of these campaigns stood a single knowledge claim first articulated in the early 1940s, namely that certain known substances kill plants. This influential claim required chemical work to prove and put into practice, but this did not change its fate in U.S. courtrooms, where it struggled to constitute invention at all.

Alison McManus is a PhD Candidate in Princeton’s Program in the History of Science, where she is writing her dissertation on chemical weapons development, secrecy, and scientific publication in the Second World War.

Further Reading:

Hasok Chang, “What History Tells Us about the Distinct Nature of Chemistry,” Ambix 64, no. 4 (2017): 360–374.

Celia Kirby, The Hormone Weedkillers: A Short History of Their Discovery and Development (Croydon: British Crop Protection Council Publications, 1980).

S. Tina Piper, “Growing a Patent Culture: Plant Hormones Research and the National Research Council,” in Putting Intellectual Property in Its Place: Rights Discourses, Creative Labor, and the Everyday, eds. Laura J. Murray, S. Tina Piper, and Kristy M. Robertson (New York: Oxford University Press, 2014).

Nicolas Rasmussen, “Plant Hormones in War and Peace: Science, Industry, and Government in the Development of Herbicides in 1940s America,” Isis 92, no. 2 (2001): 291–316.

James R. Troyer, “In the Beginning: The Multiple Discovery of the First Hormone Herbicides,” Weed Science 49, no. 2 (2001): 290–297.

David Zierler, The Invention of Ecocide: Agent Orange, Vietnam, and the Scientists Who Changed the Way We Think About the Environment (Athens: University of Georgia Press, 2011).

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