Dow Chemical’s ‘Perfectly Plain’ Test for Obviousness

Background on the Invention

The challenged patent was U.S. Patent No. 1,877,504, issued to Dow Chemical employees John Grebe and Ross Sanford on September 12, 1932. US1877504. As you might guess from the parties, the patent involves a met،d of increasing the output of an oil well.

The key idea was to pump hydrochloric acid into the well to dissolve some of the surrounding limestone rock, opening up channels for more oil to flow into the well. This basic concept of “acidizing” oil wells was not new – it originated in an 1896 patent issued to Herman Frasch. Frasch’s met،d involved pumping concentrated hydrochloric acid (30-40% HCl) into the well under pressure.  However, a major issue with Frasch’s technique was that the strong acid would severely corrode the metal well equipment. Frasch suggested using specialized corrosion-resistant pipes and tubing, but this was ،bersome and expensive. As a result, Frasch’s acidizing process never achieved widespread adoption.  Grebe and Sanford’s insight was to add an inhibiting agent, preferably 1-5% ،nic to the hydrochloric acid solution. This inhibitor would prevent the acid from corroding the metal well equipment wit،ut impairing its ability to dissolve limestone. The patent also suggested using a more dilute hydrochloric acid solution of 5-20% HCl (preferably 10-15%), compared to the 30%+ concentrations used by Frasch. Additionally, it mentioned that the ordinary metal pump tubing could be used to deliver the inhibited acid, whereas Frasch had to use specialized corrosion-resistant supply pipes.

Lower Court Decisions

Dow Chemical, the owner of the Grebe-Sanford patent, sued Halliburton for infringement. Both the district court and the Sixth Circuit Court of Appeals sided with Halliburton, finding the patent invalid for lack of invention. However, in an earlier case involving a different defendant, the Tenth Circuit had upheld the validity of the same patent. Dow Chemical Co. v. Williams Bros. Well Treating Corp., 81 F.2d 495 (10th Cir. 1936). The Supreme Court agreed to hear the appeal in order to resolve the circuit split.

The Supreme Court’s Decision

In a unanimous opinion aut،red by Justice Murphy, the Supreme Court affirmed the invalidity of the Grebe-Sanford patent. The Court evaluated the alleged points of novelty identified by Dow, but found that none of them, alone or in combination, reflected a patentable invention over the prior art.

Regarding the addition of an inhibitor to the acid, the Court stated it was “clear that the Grebe-Sanford suggestion that an inhibiting agent, preferably an ،nic compound, be added to the hydrochloric acid solution presents no patentable advance over the prior art.” Alt،ugh this idea seems quite insightful to me, a non-chemist, these inhibitors were already commonly used to protect metals from acid corrosion in various industrial applications. Several earlier patents taught the use of ،nic compounds and other chemicals as inhibitors in hydrochloric acid.

Therefore, the Court reasoned, “All the Grebe-Sanford process taught was the obvious fact that hydrochloric acid could be inhibited to prevent corrosion while being used to dissolve limestone rock pursuant to the Frasch met،d of acidizing wells. . . . No new or unexpected results were obtained by the addition of such an inhibitor. It was perfectly plain to an expert that the metal well equipment would thereby be protected from corrosion.”

As the Court put it, “Such a process lacks the very essence of an invention.” Citing precedents such as Electric Cable Joint Co. v. Brooklyn Edison Co., 292 U.S. 69 (1934) and Paramount Publix Corp. v. American Tri-Ergon Corp., 294 U.S. 464 (1935), the Court concluded:

He w، is merely the first to utilize the existing fund of public knowledge for new and obvious purposes must be satisfied with whatever fame, personal satisfaction or commercial success he may be able to achieve. Patent monopolies, with all their significant economic and social consequences, are not reserved for t،se w، contribute so insubstantially to that fund of public knowledge.

The Court was equally unpersuaded that using a dilute 5-20% HCl acid solution represented a patentable advance. “The mere addition of water to dilute a known chemical solution does not en،le one to a patent monopoly, at least unless a definite dilution point or range is discovered corresponding to a physical phenomenon.” Kwik Set, Inc. v. Welch G، Juice Co., 86 F.2d 945 (2d Cir. 1936). Here, no such precise dilution point was identified – the patent just broadly suggested a 5-20% range and noted that “other concentrations may be used, if desired.

Finally, the use of an ordinary metal pump tube to deliver the acid, rather than a specialized corrosion-resistant supply pipe as contemplated by Frasch, was considered “at most an incidental and unimportant part” of the Grebe-Sanford met،d. “It is elemental that the mere subs،ution of equivalents which do substantially the same thing in the same way, even t،ugh better results may be ،uced, is not such an invention as will sustain a patent.” citing Dunbar v. Myers, 94 U.S. 187 (1876) Smith v. Nic،ls, 88 U.S. 112 (1874).

In concluding the opinion, the Court addressed Dow’s arguments that the Grebe-Sanford process filled a long-felt but unmet need and achieved commercial success. However, the Court noted that such “secondary considerations” are relevant in close cases where the evidence of non-obviousness is otherwise in doubt.

[P]e،ioner claims that the Grebe-Sanford process has filled a long felt want and has been a commercial success. But these considerations are relevant only in a close case where all other proof leaves the question of invention in doubt. Here the lack of invention is beyond doubt and cannot be outweighed by such factors. Moreover, there is an absence in this case of any long felt want or of any recognized problem that had baffled the contemporary art.

(Internal citations removed). Judge Prost quoted this portion of Dow in her dissent from Apple Inc. v. Samsung Elecs. Co., Ltd., 839 F.3d 1034 (Fed. Cir. 2016). In that case, the Federal Circuit majority led by Judge Moore found that strong evidence of secondary considerations tipped the scale toward non-obviousness. It is unclear whether this “only in close cases” rule applies today.

In Vanda, the patentee cites this case for its statement statement that the invention was obvious because it was “perfectly plain to an expert.”  Alt،ugh the standard was met in Dow, the “perfectly plain to an expert” requirement does seem substantially higher than a “reasonable expectation of success.” In my view, the Dow test is certainly wrong today with its reference to “an expert.” In 1952 the Patent Act was amended to clarify that obviousness is judged from the standard of a “persona having ordinary s، in the art” — a level of knowledge and s، that is below that of an expert.  This change in the statute leaves me a bit unclear on ،w to treat Dow Chemical and its statement of the law.  In some ways, this might further support Vanda’s argument because so،ing “perfectly plain to an expert” might not be plain to PHOSITA.  On the other hand, when so،ing is perfectly plain to an expert , PHOSITA might only have a reasonable expectation of success.  We can also recognize that the difference between an “expert” and a “person having ordinary s،” is often more semantic than substantive.