The Application

Patent Prosecution

Patent rights exist only when the Patent and Trademark Office (PTO) issues a patent.  The process of applying for a patent is called patent prosecution.   

Patent Application

The patent application includes a specification that comprises a written description and claims.

Claim Interpretation
Disclosure Requirements

The claims set forth the subject matter over which the inventor is claiming property rights.  The claims must state with particularity the boundaries, or limitations, of the property rights that the inventor claims in the invention.


Interpretation of claims is from the perspective of a PHOSITA.  From that perspective, courts examine intrinsic evidence, including the words of the claims, the remainder of the specification, and the prosecution history.  Courts also may examine extrinsic evidence, such as dictionaries, treatises, and testimony of an expert and the inventor.  Intrinsic evidence weighs more than extrinsic evidence in determining the meaning of claims.

Written Description

The written description must employ full, clear, concise, and exact terms.  It must describe everything that is claimed.

The enablement requirement necessitates that the written description enable a Person Having Ordinary Skill In The Art (PHOSITA) to make and use the invention that is contained in every claim, without having to perform undue experimentation.  Not all information about the invention need be disclosed if a PHOSITA would know that information.


The written description must set forth the best mode of carrying out the invention.  Courts apply a two-prong test: First, did the inventor hold a belief about the best mode at the time she filed the application?  Second, did the written description disclose the best mode for a PHOSITA? 

Best Mode

There are three requirements dealing with disclosure in the specification:

(1) Written Description;

(2) Enablement; and

(3) Best Mode.

Practice Problems

Question 1

Billy Bo-Bob invents a product that cleans moss from house siding. He applies for a patent on his invention. The written description of his application explains how to apply the product to ensure a full cleaning of the moss. The claims section of his application includes the following:

(1) A cleaning solution for cleaning moss off of house siding, comprising any liquid that is effective at cleaning moss off of house siding.

(2) The cleaning solution of claim 1, wherein said solution is mixed with carbonated soda pop.

Question: On what basis would the PTO deny these two claims?

Question 2

Larry Lawrence has invented a method for controlling blood sugar levels of persons with diabetes. He applies for a patent on his invention. One of Larry’s claims uses the word bolus, stating:

(1) A method of reducing elevated blood-sugar levels in diabetics, comprising the step of taking a bolus 30 minutes after eating any carbohydrate.

The ordinary meaning of bolus is a small, rounded mass of chewed food. In the context of diabetes, however, a physician would understand the term to mean a dose of the insulin drug.  Suppose that in the written description, Larry has stated that “bolus” is to mean an eight-ounce glass of water.

Question: How will a court interpret the meaning of bolus in the stated claim?

Question 3

Sally Forth has invented a machine that turns ordinary garbage into gasoline in a few minutes. She applies for a patent on her invention. In the written description of her application, Sally describes in full detail how to make and use the machine. Any mechanical engineer would be able to make and use the machine after having read her specification. She claims only the following:

“All means for transforming garbage into gasoline.”

Question: Based on this information, is it likely that Sally will be granted a patent on her invention?

Question 4

You are an attorney for Lana Lazy. Lana has learned about an invention that her brother-in-law, David Dorkus, has recently created. David has not yet filed for a patent application, so Lana would like to apply for a patent on the invention before David does.

Question: If you immediately file for a patent on Lana’s behalf, can she obtain a patent on the invention?


Answer to Question 1

The two claims fail the enablement requirement. The first claim purports to cover “any liquid” that could accomplish the desired result, and neither the claims nor the written description provides any detail as to the composition of even one such liquid. The second claim is invalid for the same reason as the first claim.


Answer to Question 2

A court will interpret bolus to mean an eight-ounce glass of water. Claims must be read in view of the written description. The written description informs the proper construction of the claims. If Larry, however, had not included that specific meaning of bolus in the written description, then the meaning of bolus to a PHOSITA would apply, i.e., a dose of the insulin drug.

Answer to Question 3

No.  Although the written description provides great detail on how to make and use the machine that Sally has invented, the written description does not fully enable the scope of the stated claim. Sally’s written description provides only one embodiment of the claim, which purports to cover all possible embodiments.  Her claim is too broad, much like Claim 8 in O’Reilly v. Morse.

Answer to Question 4

No. Only if the inventor, David, were to assign his right to patent the invention to Lana could she apply for the patent.  Otherwise, only the inventor may file for a patent on an invention.