In short, a patent search is a search of the prior art (see above) to determine if an invention can be patented. The more detailed answer follows. To be patentable, an invention must be different enough from the prior technology (“prior art”) to deserve the grant, by the U.S. Patent and Trademark Office, of the exclusive rights awarded by a patent (what constitutes “different enough” is another and complicated topic to be discussed elsewhere). Since patent applications can be expensive, it is sometimes desirable to obtain some information about whether the invention is different enough that it would have a reasonable probability of being patented if a patent application were filed. To accomplish this, a patent search can be performed in the U.S. Patent and Trademark Office and can also be extended to searching in patent offices of other countries and to several patent searching internet web sites both in the U.S. and internationally. A reasonable amount of time is spent, usually a few hours, trying to find patents or publications showing technology that is similar to the new and unique features of an invention. The more time that is spent searching, the more costly the search and the more likely that prior art similar to the invention would be found. Several days could be spent searching, but the considerable expense of that is usually not justified because an extensive search could be more expensive than having a patent application prepared and filed. No matter how extensive the search, there is always a risk that close prior art exists but is not found in a search. And that prior art could later be found by a patent examiner who is deciding whether the invention qualifies for a patent. In addition to patents, documents that are printed or displayed on web sites also can be prior art. These are often not searched because of the cost.

Patent attorneys typically employ professional patent searching firms to perform the patent search. Such firms have experienced searchers who are familiar with the various ways of finding prior art, especially online in various proprietary databases. Some of those search firms also contract to search for the U.S. Patent & Trademark Office.

The prior art patents and other publications if any, that are found in the search are studied by a patent attorney and an opinion estimating the probability of obtaining a patent is then written and delivered along with copies of the closest prior art found in the search.

The cost of a practical search and opinion is ordinarily approximately $3,000.00 but could be more or less depending principally upon the technical complexity of the invention and also on the nature of the invention. That cost represents a quantity of searching effort that is commonly regarded as a reasonable compromise between the cost and the thoroughness of the search.

Obviously, before a search can be performed it is necessary that the patent attorney be educated about the invention. The better and more complete the disclosure of the invention to the patent attorney, the better the search. After the disclosure of the invention to the patent attorney, a more exact cost estimate can be given.