Without Undue Experimentation vs Without Any Experiments

by Dennis Crouch
I was rereading the Supreme Court’s recent enablement decision of Amgen Inc. v. Sanofi , 598 U.S. 594 (2023) and was struck by the Supreme Court’s statement that its 19th Century decision of Wood v. Underhill , 46 U.S. 1 (1847) “establish[ed] that a specification may call for a reasonable amount of experimentation to make and use a patented invention.”  This statement from Amgen is surprising because Chief Justice Taney’s decision in Wood includes a seemingly contrary statement that bars any experimentation :
The specification must be in such full, clear, and exact terms as to enable any one skilled in the art to which it appertains to compound and use the invention; that is to say, to compound and use it without making any experiments of his own .
Wood , 46 U.S. at 4.  Although Wood does allow for some extrapolation from the specification disclosure to cover broader claims, it expressly holds that a patent is void if it requires additional experimentation to understand its scope.

The contrary statement in Justice Gorsuch’s Amgen opinion appears largely lifted from the United States amicus brief in the case, which argued “ Wood and Minerals Separation establish that a patent does not violate Section 112(a)’s enablement requirement merely because its specification requires some degree of experimentation to account for the nature of the patented invention or the field in which it arises.”  Although the US brief acknowledged the “seemingly categorical nature of Wood ‘s articulation of the governing law” it then argues that Wood permits experimentation. The brief appears to conclude that by saying “without making any experimentation,” the Supreme Court in Wood actually meant that “undue” or “unreasonable” experimentation is prohibited. To understand the apparent contradiction, I thought it would be helpful to dig into some of the details of the case.


Background of the Invention
Wood’s U.S. Patent No. 97, originally issued in 1829 and later reissued in 1836, was directed to a process of mixing pulverized anthracite coal dust with clay before molding the bricks or tiles. In his patent specification, Wood stated:
Take of common anthracite coal, unburnt, such quantity as will best suit the kind of clay to be made into brick or tile, and mix the same, when well pulverized, with the clay before [it] is moulded; that clay which requires the most burning will require the greatest proportion of coal-dust; the exact proportion, therefore, cannot be specified; but, in general, three fourths of a bushel of coal-dust to one thousand brick will be correct. Some clay may require one eighth more, and some not exceeding a half-bushel.
The basic idea here is to use pulverized coal as a sort of internal fuel that is mixed throughout the brick or tile material, allowing it to burn more efficiently and evenly during the firing process.  Wood claimed that this composition provided benefits of “saving of fuel, and the more general diffusion of heat through the kiln, by which the whole contents are more equally burned.”
The Lower Court Decision
In 1842, Wood sued William Underhill and Aschel Gerow for infringement.  This was a big case with Wood alleging that the defendants had made 100 million bricks and 100 million tiles using his patented process. Wood requested damages of $30,000, being triple his alleged actual damages of $10,000.  This is over $1 million in 2024 dollars based upon a 2% annual inflation rate.
At trial, the defendants argued that Wood’s specification was insufficient “because no certain proportion for the mixture is pointed out, but only that such quantity of coal must be taken as will best suit the kind of clay to be made into brick or tile.” They contended that there was “no fixed rule by which the manufacturer can make the mixture, but that must be ascertained by experiments upon the clay” and that the claiming clause was “too vague and uncertain to sustain a patent.”  The circuit court agreed with the defendants and instructed the jury that the specification was too vague and uncertain to support the patent. The jury found for the defendants, and Wood appealed to the Supreme Court.  At the lower court, the defendants also argued that Wood’s claimed invention was not new, having been known and used by numerous individuals in England, Wales, Canada and the United States prior to Wood’s alleged invention, but that issue was left moot by the decision that the specification was insufficient.
The Supreme Court’s Decision
In its decision, the Supreme Court reversed in a unanimous opinion authored by Chief Justice Taney. The key issue, as framed by the Court, was “whether his description of the relative proportions of coal-dust and clay, as given in his specification, is upon the face of it too vague and uncertain to support a patent.”
The Court acknowledged that if a specification “gives only the names of the substances which are to be mixed together, without stating any relative proportion” or if the proportions “were stated ambiguously and vaguely” then it would be proper for a court to declare the patent void. This would be the case when “it would be evident, on the face of the specification, that no one could use the invention without first ascertaining by experiment the exact proportion of the different ingredients required to produce the result intended to be obtained.”
However, the Court found that this “degree of vagueness and uncertainty” did not exist in Wood’s specification. The Court noted that Wood provided “a certain proportion as a general rule; that is, three fourths of a bushel of coal-dust to one thousand bricks.” While Wood mentioned that some clay may require slightly more or less coal dust, the Court regarded these as “exceptions to the rule he has stated; and as applicable to those cases only where the clay has some peculiarity, and differs in quality from that ordinarily employed in making bricks.”
The Court explained that “the general rule is given with entire exactness in its terms” and the variations mentioned seemed intended “to guard the brick-maker against mistakes, into which he might fall if his clay was more or less hard to burn than the kind ordinarily employed in the manufacture.” The Court acknowledged the possibility that clay qualities may differ so widely that the specification would be of no value and the invention could not be used without experimentation, but stated that this was not apparent from the face of the specification and was a question of fact for the jury to decide based on expert evidence. But the bottom line is that:
The Circuit Court therefore erred in instructing the jury that the specification was too vague and uncertain to support the patent,—and its judgment must be reversed.
The case was remanded for a new trial.  As suggested here,  Wood v. Underhill highlights important distinctions between legal and factual issues in patent cases and the respective roles of the judge and jury.


One key issue was whether the vagueness and uncertainty of Wood’s specification rendered the patent invalid on its face. The Supreme Court treated this as a question of law for the judge to decide. The trial judge had ruled the patent invalid due to the lack of a precise proportion of coal dust, and the Supreme Court reviewed this ruling without deference.  However, the Supreme Court also noted that if a specification’s adequacy depends on underlying factual questions, such as whether a person skilled in the art could practice the invention without undue experimentation, then those questions should be put to the jury. The Court explained:
In patents for machines the sufficiency of the description must, in general, be a question of fact to be determined by the jury. And this must also be the case in compositions of matter, where any of the ingredients mentioned in the specification do not always possess exactly the same properties in the same degree.
So while the ultimate legal conclusion on a specification’s adequacy is for the judge, subsidiary factual issues about the state of the art and the predictability of the results may need to be resolved by the jury.  I have not been able to find what actually happened on remand in the case.


Reconciling Wood and Amgen
At first glance, Chief Justice Taney’s statement in Wood that the specification must enable a skilled artisan “to compound and use it without making any experiments of his own” seems directly at odds with Justice Gorsuch’s statement in Amgen that Wood allows for “a reasonable amount of experimentation.”  But I think that the better way to see these cases as both standing for the a fundamental principle – a patent specification must provide enough clarity that a skilled artisan can practice the claimed invention, but it need not spell out every last detail.
In his 1953 patent law treatise, John Paxton Norman provided a narrow treatment of Wood , concluding that it required disclosure at least some embodiments that can be created without experimentation.  John Paxton Norman, A Treatise on the Law and Practice Relating to Letters Patents for Inventions (1853). He cites Wood for the proposition that the invention is not patentable “if the qualities of the ingredients generally differ so widely that the rule given is of no value, or if the improvement cannot be used without ascertaining in every case by experiment the proportions to be employed.” Id.  This interpretation of Wood also pushes against the full scope enablement  and written description requirement that has become so popular.