Patent searching is by no means an exact science. With a plethora of search tools and consulting practices to choose from, there is no “one size fits all” to guarantee the successful capture of all relevant prior art.
But if you follow these best practice guidelines, the chances of obtaining more targeted, accurate results will certainly increase:
- Search Reason for Allowance or last claim amendment. In validity searching, if you have only a limited time, search only the reason for allowance and/or last claim amendment. If you can locate art that overcomes the Examiner’s reason for allowance or last claim amendment it will be possible to invalidate the claims you are searching. It will be a combination argument with a good reference perhaps cited already by the examiner and the new reference you have found.
- Citation search the family members. Citation searching is a useful tactic when keyword and/or classification searching may not produce optimal results, perhaps because the invention is not in a well-classified area or has many different possible applications. Most searchers will citation search the patent documents cited in prosecution; but documents cited in prosecution of the family members also should be searched. Use the Derwent World Patents Index (DWPI) (or other non-restricted family grouping) as your definition of “family” to keep result sets manageable. Multi-generations can be helpful where keywords and/or classes are not yielding relevant art. In validity searching, you can search the backwards citations from the forward citations of the issued patent, then filter by critical date. This should locate possibly useful art. Citation searching is especially useful for hard-to-find subject matter or where keywords do not seem helpful.
- In validity searches, review the Examiner’s final search history. Don’t look at results the Examiner has already seen! In US prosecution, the Examiner performs multiple searches. When a US patent application receives a notice of allowance, it is based on a search conducted by the patent examiner. The Examiner’s search history is published in the Image File Wrapper, available to the general public.