When faced with a potentially infringing competitor, holders of design patents of course need to know the scope of their design patent. The question is an understandable one, after all, unlike a utility patent, there is but one claim—typically of a form along the lines of the following: “I claim the ornamental design as shown in the attached drawings.” There is rarely, if ever, any further explanation on the face of the patent, and it is easy to empathize with the head-scratching this format causes for a patent holder, particularly in the business context, trying to make reasoned decisions about enforcement.
A recent case, Egyptian Goddess, has changed the rules for infringement: Whenever an ornamental design is substantially similar to the design patent in question in the eyes of an ordinary observer (reasonably familiar with the prior art, i.e., preexisting patents, publications and products offered for sale or in public use), that design infringes.
While this in some respects simplifies enforcement and clarifies the law, it does not necessarily clarify all issues of scope for the holder of a design patent. The reason: we have to look at similarity in the eyes of the ordinary observer “in light of the prior art.” We need to know this to answer the question, what does my design patent protect? In close cases, we may have to know it to answer, does this competitor’s product infringe?
For a moment, indulge an affinity for physics by considering a metaphor that may prove instructive. The earth, like all massive objects in the universe, has a gravitational field. As one moves away from the earth, the strength of the gravitational field diminishes until, eventually, at an adequate distance, it becomes negligible. The point being, the field has a gradient—it drops off with distance. Of course, the earth is not alone—nearby heavenly bodies also have their own gravitational fields, and there are regions where the fields of the earth and the nearby bodies overlap.
With that model in mind, consider your design patent to be the earth, while all the other nearbyheavenly bodies are instances of prior art. Instead of a gravitational field, imagine a “similarity” field; the closer to your design patent, the stronger your similarity field. Conversely, the same would be true as to all the other instances of prior art and their respective similarity fields. This means that the entire universe of open space can be characterized into one of three zones: (1) the space where your similarity field is at least somewhat stronger than all others; (2) the space where some prior art’s similarity field is stronger; and (3) the space where all fields are negligible (i.e., the accused design is “remote” from the patented design and not similar).
When it comes to infringement, where do the potentially infringing designs appear in this universe? If the potential infringer appears in zone 2 or 3, guess what? There is no infringement. However, any design appearing in zone 1, where your similarity field prevails over all others, then the patent holder has an argument, at least, that infringement has occurred. The question then becomes a matter of magnitude; that is, whether that potentially infringing design is substantially similar to your design patent.
Having set up this model, here is—admittedly—its fundamental flaw. Unlike our methods for measuring gravity, we have been provided with a somewhat unpredictable device for taking measure of our similarity field: a jury of human beings. These are the people who tell us the conclusion that an ordinary person would draw when comparing the similarity of your design patent, the potential infringer, and the universe of prior art. Luckily, as the patent holder, you add some certainty to this process by choosing the technician who will be putting the required information into that device: your patent litigation attorney.