Sometimes a great invention does not fit into the traditional categories understood by patent attorneys. Consider improvements that do not necessarily make an advancement to a single product, but rather to a group of products. This may include a new component design that enables different sizes of a product to be made more efficiently with common parts, or a special grouping of product made available to consumers in a way that enables easier selection. These types of improvements can span a wide range of technologies, from vehicles to footwear. Conventional thinking generally eschews pursuing protection for such inventions.  

However, there is generally no prohibition on claiming product lines. One example from the footwear arts is illustrated by U.S. 8,302,330.  This patent relates to a slipper product line with at least nine models of slippers, at least three different sizes, and at least three levels of firmness. Each of the slippers comprises the typical elements of a slipper, but differs in size and the cushioning properties of a support portion. This patent illustrates a classic example where product lines are the key to patentability, as any given slipper, by itself, is not unique. Thus, the purported novelty of this case relates to how the slippers are categorized and classified.

While it may be possible to successfully draft and prosecute such product line claims, one area of caution relates to drafting the claims in a way to successfully enforce the resulting patent against a competitor.  Care must be taken to consider the issues of joint infringement, and whether it will be necessary to rely on contributory or inducement theories of liability. It may be that dealers or retailers provide the only source of direct infringement, depending on the business practices in the given industry. Also, it remains to be seen whether Section 101 could be applied to such inventions under the theory that they cover abstract ideas. 

In any event, patent professionals should remember product lines as another tool that may be used in the right situation to provide valuable protection.