To be patentable, an invention must achieve a useful purpose.  This is the requirement for utility.  Related to that requirement is the non-obvious requirement: the means for achieving the useful purpose must not be obvious to a person having ordinary skill in the art (PHOSITA). 
























Only a minimal degree of utility is required.  However, neither a purpose of existing nor a purpose of being garbage that fills a garbage dump would satisfy the requirement of a minimal degree of utility.

Minimal Degree of Utility

To provide the necessary utility, an invention must actually work for its intended purpose.  In this sense, the invention must be operable.

Works for Intended Purpose

There is no requirement that the utility yield social benefit.

Social Benefit Not Required
Specific & Substantial

For an invention to be useful, the invention must yield a specific and substantial utility.  Specific and substantial means that the invention works for a particular practical purpose.  The purpose must be identifiable.



Utility &


Four factors inform non-obviousness:
(1) the scope and content of the prior art;
(2) the differences between the prior art and the claims;
(3) the level of ordinary skill in the pertinent art; and
(4) secondary considerations (commercial success; long felt needs unsolved; failure of others).

Factors to Consider

Courts consider whether a PHOSITA would think to combine elements from the prior art in order to determine the obviousness of a claim.

Combining Elements in Prior Art

To be patentable, an invention must not be obvious to a PHOSITA. The invention must be significantly different from the prior art.

TSM Test

The TSM test examines whether the prior art teaches toward, suggests, or motivates a combination of elements in the prior art.  The Surpeme Court (KSR) has rejected a rigid application of this test.  Combining elements from the prior art might be obvious even if the prior art does not teach toward, suggest, or motivate that invention.

Practice Problems

Question 1

William seeks to patent a method for exercising cats. His method consists of pointing a laser at a wall and moving it so that the cat will chase the light.

Question: As between the non-obvious and useful requirements, which is a stronger argument against William obtaining a patent?

Question 2

Matthew submits a patent application for a machine that produces perpetual motion without any input of energy. The machine, however, does not actually work.

Question: Does this fulfill the utility requirement? Why or why not?

Question 3

Marcy makes a hat that has a large hole in the top for gaining sunlight exposure.

Question: Would this fail for lack of utility, non-obviousness, or both?

Question 4

Suppose the following is true: Ever since the invention of the solar panel, engineers have been trying to develop a building material that captures the sun’s energy. They have been seeking to make the entire outer structure of a building from material that will capture the sun’s energy much like a solar panel.

One engineer named Byron makes a great discovery: the solar panel itself can serve as the outer structure of a building. That is, Byron discovers that solar panels can be used for the outside walls and roofing of buildings. As a result of this discovery, Byron seeks a patent on the method of making a building from solar panels. While waiting for the issuance of the patent, Byron’s method of constructing building from solar panels achieves immediate commercial success.

Question: Will Byron’s claim fail for obviousness?

Answer to Question 1

Non-obviousness. A PHOSITA who deals with cats likely knows that shining a light on a wall will make a cat chase it, thereby providing the cat exercise. As for utility, the invention works for an identifiable, practical purpose—even if the invention may have a low degree of utility.


Answer to Question 2

No. To fulfill the utility requirement, the claimed invention must work for its intended purpose, i.e., be operable. The perpetual-motion machine is not operable.

Answer to Question 3

Non-obviousness only. The hat lacking a hole has a specific and substantial benefit, albeit minimal. The fact that the utility is of only minimal degree and that the utility lacks societal benefit does not matter. The invention realizes an intended purpose: the hat allows for sunlight exposure—a particular practical purpose. On the other hand, the claim would likely fail for lack of non-obviousness (if not for lack of novelty): placing a hole in the top of a hat so as to gain exposure to sunlight probably would be obvious to a person skilled in the art of hat-making.

Answer to Question 4

No. The prior art would consist of information about solar panels and information about construction of buildings. The combination of these prior art references would not be obvious to a PHOSITA. Evidence supporting the conclusion of non-obviousness consists of the fact that engineers have been trying without success to invent a means for achieving what Byron’s patent claims, that this need has existed for a long time without being solved, and that Byron’s methodology became an immediate commercial success.