Designing Around Another Patent

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To design or build a device or process that is similar to but doesn’t infringe on an invention protected by a patent is referred to as “designing around” the patent. The scope of protection acquired under a patent is determined by the wording of the patent’s claims. Thus, any device, process, or substance containing the same elements described in a patent’s claims can be said to infringe the patent. Conversely, a device or process that contains fewer or different elements does not infringe the patent (technically, the patent’s claims do not “read on,” or literally describe, the infringing device). Therefore, by studying the claims associated with a specific patent, it is often possible to build or design a device or process very similar to that described in the patent without legally infringing the patent’s claims.

Example: Fred invents and patents a small radiator-type device that uses hot water to dry and warm towels. One of the claims for his invention describes it as consisting of plastic. Bonanza Bathroom Products (BBP) creates a similar device but uses a metal alloy that doubles the ability of the device to retain heat. BBP probably has not infringed Fred’s patent, because it designed around the invention by using a different element that produces a different result.

To try to prevent such “designing around” activity, Fred’s patent claim should have been broader to start with. Instead of limiting his invention to plastic, Fred’s claim might have described “an inflexible means through which hot water can be channeled at normal domestic water pressures, the heat retained over a period of time, and towels folded over for the purpose of drying.”

There is one important legal restriction on the ability to design around a patent claim. A court can decide that the differences in the basic elements of the two inventions—in the previous example, the type of substance used and the extra heat retention—are immaterial (unimportant) to the overall invention. In that event, infringement will have occurred under the doctrine of equivalents, which allows infringement to be found when two inventions work in the same way to produce substantially the same result.