Why search old patents:
Under U.S. law (35 U.S.C. 102), no patent will issue for an invention that was previously made by another. Nor will a patent issue if the applied for invention is only an obvious improvement over what already exists (35 U.S.C. 103). Thus, in order to determine whether an invention is patentable, it is necessary to know what has already been invented (known as the "prior art").
The prior art includes all previously issued patents, as well as technical documents, journal articles, and even non-written physical materials. Thus, a new bicycle could not be patented if the same bicycle had been sold in the 1950s, even if there had never been a patent filed on that bike.
Considering the vast scope of the prior art, it is impossible to know for sure whether an invention is truly patentable. However, because so many items have been patented it is often useful to examine old U.S. patents to see what else is out there. Very often, if a new invention has never been the subject of a patent application, it has also never been made before and is elible for patent protection. Thus, many inventors will search prior patents extensively before spending any money on a patent application.
In most cases, your patent attorney will recommend that a patent search be conducted before filing your application. There are two primary benefits for performing the search at this time. First, such a search may identify prior art that will prevent a patent from issuing on your invention. In this case, the money spent on the search will prevent wasting money on the cost of drafting and filing a patent application on that invention. Second, a prior art search will identify the closest prior art to an invention. This information is invaluable to a patent attorney as they draft your patent application, as it ensures that the patent application will be drafted as broadly as possible without being so broad as to cover the prior art.
There are several caveats to the usefulness of patent searches. First, it must be remembered that patent applications are usually kept confidential until they are published eighteen months after the filing date of the application. Because unpublished applications are not available for searching, a patent search will never reveal recently filed patent applications. Nonetheless, these secret patent applications can, and frequently do, prevent patent applications from becoming issued patents.
In some cases, it may not be necessary to conduct a detailed patent search. For example, an expert in a narrow area of technology may already have a detailed understanding about what everyone else is doing in her field of expertise. A company may decide to rely upon the opinion of their own expert rather than conduct a detailed patent search on a new invention.
Internet Patent Searches:
There are many very good resources for searching published and issued patent applications. Some of the best search engines (ranked according to personal preference) are:
Expert Patent Searches:
The most effective way to search for prior art is to hire a professional patent searching company to perform a search on your behalf. The cost for a patentability search appropriate for a new patent application is typically between $700 and $1,000.
Individuals and small companies can hire a patent search firm directly. Many firms can be discovered simply by searching the Internet for "patent search firm." The result from the search will be a list of patent references that are related to your invention. Alternatively, you may choose to hire a patent attorney to conduct the search and review the results on your behalf. In many cases, the patent attorney will hire an outside company to perform the patent search. The results of the search are then returned to your attorney, who then analyzes the results. This analysis can be used to form a written or verbal opinion as to whether your invention is patentable. In most cases, the cost for having an attorney review the results returned from a patent search firm will be between $1,000 and $3,000.
More information on patent searching is found in Bitlaw's Guidance section, including when one should and should not conduct a patentability search, a fuller explanation on the benefits of conducting a patent search, and a consideration of the benefits and risks of low-cost patent searching options.