Regardless of the method of inventing used, detailed records of concepts, test results, and other information related to creating your invention should be maintained. Proper record keeping is important because it can be used as proof of the conception date – a.k.a. the invention date. It should be noted that mailing yourself a sealed letter with invention documents enclosed is not an accepted method of proving your invention’s conception date for the United States Patent & Trademark Office (USPTO).

The conception date is important since it can be utilized to argue against prior art cited by the USPTO. The conception date is also important when an interference is initiated to prove which inventor was the first to create the invention. Detailed records are also evidence that the inventor was diligent in developing the invention. It should be noted that a prototype is not needed for proof of the conception date.

The conception date may be relied upon as the date of invention for determining patentability and priority only if the inventor exercised due diligence in reducing the invention to practice. This is accomplished by the inventor exercising continuous activity from before the reduction to practice date of another invention to the date of reduction to practice. Reduction to practice may be accomplished by either: (i) filing a patent application, or (ii) constructing a prototype. Continuous activity does not mean the inventor has to work on the invention every waking minute.

To establish diligence, the person must account for the entire critical period from the time just prior to another’s conception. In determining priority, there is no race of diligence. The first to reduce to practice prevails regardless of lack of diligence unless the second to reduce to practice shows sufficient diligence.

Detailed record keeping is one of the most important parts of the invention process, yet few inventors maintain adequate records of their invention. The following information provides a proposed outline for maintaining invention records. Neustel Law Offices, LTD also has an Invention Recording Document that you may utilize for recording your invention.


All inventors, whether individual inventors or employees of a business, should maintain a bound notebook. The information in the notebook is useful proof of when an invention was made, and whether the inventor was diligent in developing the invention.

A good notebook entry also can be helpful in proving that an invention is not obvious and was developed independently, without copying a competitor’s product or patent. The probative value is not nearly as great, however, if a loose-leaf notebook is used in which pages are easily inserted or removed. It is also important to line through any blank portion of the pages of the bound notebook.

Employers should have a secured location where both completed and uncompleted notebooks may be stored. Also, each notebook should be assigned a consecutive number to identify each notebook. Records of when each notebook was taken from the secured location and placed back in the secured location should also be maintained.


Every entry in the bound notebook should be signed and dated by the participants, indicating the particular project with which the entry is associated and, if possible, the entry should be signed and dated by an unbiased witness or Notary Public. It is often advantageous to include a header on each notebook entry such as:

Project No.:


The value of an entry into a bound notebook is directly proportional (i) to the specificity of the entry, (ii) to the care taken to date and sign each entry, and (iii) to whether each entry was read, signed and dated by a witness. Therefore, each notebook entry should clearly identify the nature of the entry with particularity and contain all relevant details. An entry such as “work on new cylinder” provides little useful information.

Entries should contain a clear and complete explanation of the manner and process of making and using the invention in sufficient detail to enable another person having ordinary knowledge in the field of the invention to make and use the invention.

All computations, sketches, diagrams, test results, etc., should be contemporaneously entered into the notebook. Notebook entries should also describe all testing performed (not just some of the testing), the particular type of equipment used, and the results of the testing, both good and bad.


All persons involved in the work, and their specific role, should be identified in the notebook entries. Unless participants are identified, it is often difficult to establish, long after the fact, those involved in particular activities. This type of information is also necessary to identify those who will be named in the patent application as the inventors. This is important because if not all of the inventors are named on a patent application, an issued patent may be declared invalid because of fraud on the USPTO.


It is important that all loose papers, such as drawings, test results, photographs of models, etc., be signed and dated, cross referenced to a particular notebook entry, and preferably, then mounted (taped or stapled) in the body of the appropriate notebook entry. Similarly, physical embodiments used to carry out various tests, such as samples, models, prototypes and the like, should be carefully labeled with a date, cross referenced to notebook entries, and retained.