United States: Determination Of Obviousness/Inventive Step In United States Of America


Non obviousness is one of the essential patentability requirements to obtain a patent in United States, as stated under section 35 U.S.C. § 103. The purpose of including a non-obviousness requirement is to encourage innovations that are not mere combination of prior art, without any technical advance.

Title 35, United States Code 103(a):

A patent may not be obtained though the invention is not identically disclosed or described as set forth in section 102 of this title, if the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art, to which said subject matter pertains.


The U.S. Patent Act of 1952 added 35 U.S.C. § 103, which effectively codified non obviousness as a requirement to obtain a patent. Hotchkiss vs. Greenwood, 52 U.S. 248 (1850), was the first US Supreme Court case to introduce the concept of non-obviousness as patentability requirement. Prior to the patent act 1952, novelty and utility were the only grounds for patentability. The Supreme Court first attempted to articulate the process for determining non obviousness in Graham v. John Deere (1966). The Court held that non obviousness could be determined by:

  • Determining the scope and content of prior art
  • Analysing the differences between the prior art and the claims at issue
  • The level of ordinary skill in the pertinent art
  • Evaluating evidence of secondary considerations. Secondary considerations include commercial success, a long felt but unmet need for a device, and the failure of others to solve the particular problem addressed by the invention in question.

Further, the Supreme Court in KSR v. Teleflex case identified a number of rationales to support a conclusion of obviousness, which are consistent with the proper "functional approach" to the determination of obviousness as laid down in Graham.

Case law:

Teleflex, Inc. sued KSR International, claiming that one of KSR's products infringed Teleflex's US 6237565 entitle "Adjustable pedal assembly with electronic throttle control". KSR argued that claim 4 of US 6237565 was obvious under 35 U.S.C. § 103 and therefore invalid. The district court ruled in favor of KSR, but the Court of Appeals for the Federal Circuit reversed the order in January 2005. However, on April 30, 2007, the Supreme Court unanimously reversed the judgment of the Federal Circuit, stating that claim 4 of US 6237565 was obvious under the requirements of 35 U.S.C. §103.


Combination of prior art elements:

One of the steps to determine obviousness is to articulate whether the claimed invention is a result of mere combination of prior art elements. It is always desirable to find, if a person skilled in the art can come up with the claimed invention by combining the elements of known methods, wherein each element would have performed the same function as it would have separately.

Sundance, Inc. v. DeMonte Fabricating Ltd is a hallmark case for revocation of patent based on aforementioned statement. Sundance, Inc invention was related to a segmented and mechanized cover for trucks, swimming pools, or other structures.

Sundance, had sued DeMonte Fabricating Ltd for infringement of their US patent 5026109. However, DeMonte Fabricating Ltd argued that claim 1 of US patent 5026109 was invalid and obvious citing two prior art references.

The first prior art reference taught a reason for making a segmented cover with ease of repair, in which a single damaged segment could be readily removed and replaced when necessary. A second prior art reference taught the advantages of a mechanized cover for ease of opening.

The Federal Circuit noted that the first reference and the second reference would perform in the same manner it would have individually, even after combination. Therefore, it was obvious for a person of ordinary skill in the art to expect that addition of replaceable segments as taught by the first reference to the mechanized cover of the other would result in a cover that maintained the advantageous properties of both of the prior art covers.

Substitution of elements to obtain predictable results

Substitution of an element by another element (analogue) performing similar function is considered as one of the grounds for determination of obviousness. In re Fout, 675 F.2d 297, 213 USPQ 532 (CCPA 1982) had claimed decaffeinating coffee or tea from fatty material. In re Fout, had substituted an evaporative distillation step for separating caffeine from oil. However, prior art disclosed an aqueous extraction step (Pagliaro) and direct distillation process (Waterman) for decaffeinating coffee or tea from fatty material. The court stated that both Pagliaro and Waterman taught a method for separating caffeine from oil and therefore, it is obvious for a person skilled in art to substitute a method for another performing similar function.

Known technique to improve similar devices:

A method is said to be obvious if it enhances a particular class of devices (methods, or products) known in the prior art by using a known technique.

In re Nilssen case, the invention was directed to a means by which the inverter can be disabled if current exceeded pre-established threshold level for a specified period. The United States Patent and Trademark Office Board of Patent Appeals and Interference rejected claims 1-4, 9-11, and 16 of Nilssen's patent application Serial No. 476,150 on the ground of obviousness citing two prior art references as provided below:

The first prior art USSR Certificate No. 729,738, described a device for indicating the high-load condition via a control means in an inverter, but did not indicate the specific manner of overload protection.

The second prior art U.S. Patent No. 3,305,793(Kammiller) disclosed disabling the inverter circuit by means of a cut off switch if there exist a high load current condition.

The federal circuit stated that it would have been obvious to one of ordinary skill in the art to use the threshold signal produced in the USSR device to activate a cut off switch to render the inverter inoperative as taught by Kammiller.

Applying a known technique to a known device (method, or product) ready for improvement to yield predictable results

Applying a known technique to a known device (method or product) for improvement of the device, and finding that the results obtained over such improvement would have been predictable by a person of ordinary skill in the art can be considered as obviousness. Nilssen case can be cited in this context as well.

Obvious to try

The concept of "obvious to try" is a quite sensible requirement for determination of obviousness. "Obvious to try" can be examined as follows:

  • The need for designing the claimed invention to solve a problem being recognised at the time of invention.
  • Existence of a finite number of known solutions for the problem recognised
  • Implementing one of the known solutions, which is obvious to a person skilled in the art for solving the problem recognised.

Pfizer, Inc. v. Apotex, Inc

Pfizer had been selling amlodipine besylate drug in tablet form under the trademark Norvasc® in U.S. At the time of invention of amlodipine besylate, amlodipine (Apotex) was known to posses similar therapeutic properties as were claimed by Pfizer for amlodipine besylate. Pfizer however, argued stating that amlodipine besylate had better manufacturing property as compared to amlodipine.

Court's decision:

The court found that a person skilled in the art would have obviously tried to formulate the salt form of the compound, if he had problems with the machinability of amlodipine and would have been able to narrow the group of potential salt-formers to a group of 53 anions known to form pharmaceutically acceptable salts, which would be an acceptable number to achieve "a reasonable expectation of success."

Known work in one field of endeavor may prompt variations of it for use in either the same field or a different one based on design incentives or other market forces if the variations are predictable to one of ordinary skill in the art

The scope and content of the prior art, whether in the same field of endeavor as that of the applicant's invention or a different field of endeavor, including a similar or analogous device should be identified to examine obviousness. Further, design incentives or market forces prompting to adaptation of the known device (method, or product); the differences between the claimed invention and the prior art encompassed in known variations or in a principle known in the prior art are important aspects for determining obviousness relating to the claimed invention. In addition to the above mentioned criteria for determining obviousness, it is also essential to know how a person with ordinary skill in the art, in view of the identified design incentives or other market forces, would have implemented the claimed variation of the prior art, and how would have been the claimed variation predictable to a person of ordinary skill in the art.

The claimed invention in Ex parte Catan, 83 USPQ2d 1568 (bd. Pat. App. & Int. 2007) was a consumer electronics device using bio authentication for enabling sub users to place orders up to a preset maximum credit over.

The first prior art (Nakano) disclosed a consumer electronics device like the claimed invention, which provided security through a password authentication rather than a bio authentication device. The second prior art (Harada) disclosed the use of a bio authentication device (fingerprint sensor) on a consumer electronics device (remote control) to provide bio authentication information (fingerprint). The third prior art (Dethloff) disclosed that it was known in the art at the time of the invention, to substitute bio authentication for PIN authentication to enable a user to access credit via a consumer electronics device.

The Board stated that a person with ordinary skill in the consumer electronic device domain at the time of the invention would have been familiar with using bio authentication information interchangeably with or in lieu of PINs to authenticate users. The Board concluded that it would be obvious to a person with ordinary skill in the art of consumer electronic devices to update the prior art password device with the modern bio authentication component and thereby gain, a secure and reliable authentication procedure.

TSM test

TSM stands for teaching, suggestion and motivation. A claimed invention fulfils the requirement of being non obviousness, if combination of know elements, which forms the invention, not motivated, suggested or taught in prior art.


The very fact that a number of approaches have been suggested to determine whether a proposed invention is obvious or not, is an evidence that determining obviousness is a complex subject. Hence, it is important for patent professionals to be abreast with the subject, so that informed advice can be provided to clients at least based on existing guidelines.

About the author: Hemanth Puttaiah has extensive experience in delivering patent consulting services in the software engineering domain. He has been offering patent specification drafting, patent analytics and patent support services to technology companies and patent practitioners in US and Europe. He has in-depth knowledge of various international treaties governing patent filing and prosecution across the globe, and advises clients on patent strategy. Hemanth started his career as a software engineer, where he worked on several open source technologies. His working experience as a software engineer prior to entering the field of IP has enabled him to add significant value to our clients in the software engineering domain. Hemanth holds a Bachelors of Engineering Degree from University B.D.T. College of Engineering. He is also a registered patent agent.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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