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The Inventor's Mentor

June 2009

Keeping an Inventor s Notebook

Most countries have a “first to file” patent code: the person who first files an invention is considered to be the inventor. In contrast, the US is a “first to conceive” country: the person who can prove that he or she has first conceived of the invention is considered to be the inventor.

The first to conceive patent law in the US leads to the need for maintaining a good inventor’s log book to show, if necessary, a progress record of your work, the nature of your invention and the dates when critical inventive steps were achieved. However be careful: there are pitfalls in relying on a logbook to assert your right to an invention:

1)       Due diligence. If an inventor needs to rely on a log book because someone else has filed for a patent before him, he needs to show that he has exercised due diligence in developing his invention from the time before the filing (or conception) by the other person, to the time of his own filing, otherwise the invention will be considered to be abandoned (35USC102g2).

2)       Enabling Description: the log book must “contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art… to make and use the [invention]” (35USC112).

3)       Best Mode: the log book must also “set forth the best mode [or example of use] contemplated by the inventor of carrying out his invention.” (35USC112). Ideally, the log book must be as well written as a patent application since it may have to be compared with an application filed by a competitor.

4)       Claims: Since your log book is unlikely to have claims, your invention will be limited to exactly what is disclosed in the log book. On the other hand, the patent application against which you are competing is likely to have claims that greatly broaden the scope of what is actually disclosed. So even though you may be considered to be the inventor, you’ll get a narrow slice of the pie, with the much larger slice going to someone else.

5)       The Responsibility is Yours: If someone files before you, it will be up to you to prove that you are the first inventor – and this may be an uphill battle, neither easy nor cheap. The standard of proof will be quite high. You will have to produce all the documents proving your case, such as witnessed logbook entries, proposals to government agencies, dated letters, detailed diagrams, computer records, purchase receipts, etc. Ideally, to avoid trouble, you should file your patent application as soon as your invention is clearly defined.

Guidelines for Maintaining a Logbook.

1)       Tamper-proof. The logbook should not allow cheating. It should have non-removable pages and be written in ink. There should not be any loose pages.

2)       Consecutive Pages. Entries should be made in consecutive pages. If a page is left partially blank a line must be drawn across the blank area.

3)       No Erasures. Entries that need to be eliminated should not be erased. They should be crossed over with a single clean line.

4)       Entries: These may include text, formulas, diagrams, sketches and milestones achieved. These may also include photographs if the photographs are affixed to pages with a non-removable glue. Diagrams, sketches and photographs should be accompanied by clearly written explanations.

5)       Entry Contents. Entries need to be clearly understandable by someone knowledgeable in the art of the invention. Entries need to show:

                     i.                                                Due diligence

                    ii.                                                Enabling description

                  iii.                                                Best mode

                  iv.                                                As many variations as possible.

6)       Entry Identification. Each entry should be identified with respect the particular invention to which it relates.

7)       Entry Dating. Each entry should be dated and the dating should be consecutive. This is necessary to establish the time of conception. Once an entry is made and dated it should not be altered at a later date.

8)       Witnessing. Periodically, the logbook should be witnessed by a notary public or someone familiar with the technology of the invention but not directly involved with it. He should be credible as he may be called later as a witness.

9)       No Mutilation. Logbooks should never be mutilated, for example by tearing out pages.

For archived newsletters and a lot of information for the small inventor go to: If you have any question you can contact me at (858)259-2226 or email me at This newsletter should not be construed as legal advice. ©2010 by George Levy.