Patent infringement can ruin a business. In patent infringement cases, the courts can slam a patent infringer with crippling damages. Furthermore, judges have legal authority to issue preliminary injunctions at very early stages of patent litigation. A preliminary injunction forbids an accused infringer from making and selling the accused product, therefore, immediately shutting down the infringer’s revenue stream. Unable to keep up with mounting legal bills, many businesses accused of patent infringement have no choice but to enter unfavorable settlements or even face bankruptcy. So what is the best defense against patent infringement? Simple: non-infringement.

What is patent infringement?

The heart and soul of every patent are the patent claims. These enumerated paragraphs at the end of each patent define the legal boundaries of the patent. An accused device or method infringes a patent claim when, and only when, every element of that claim is present in the accused device or method. For example, let’s consider a fictitious patent claim covering a pencil:

So what exactly does this patent claim cover? The annotated image below illustrates each element of the claim:

An owner of this fictitious patent may boast that he or she “patented for pencils” and may even accuse anyone selling pencils of patent infringement. As patent attorneys, we run into these scenarios quite often. Many patent owners over-exaggerate the extent of their patent rights. Just because someone patent a pencil, does not mean that every pencil will infringe that patent.

To establish infringement, a patent owner must prove that the accused device (or method) has every single element recited in a patent claim. If at least one element is missing, there is no infringement. Returning to the pencil example provided above, the patent claim has several limitations. First, the pencil must have a wooden body. Second, the wooden body must have a hexagonal cross-section. Third, the writing core of the pencil must be graphite. Fourth, the pencil must have an eraser. Fifth, the eraser must be attached to the pencil using a coupling. By eliminating at least one of these elements, a pencil manufacturer can avoid patent infringement. Thus, although this exemplary patent covers a pencil, it does not cover every pencil. Simply removing the eraser or making the pencil round would negate patent infringement.


A patent infringement accusation can be a serious threat. However, just because the threat is serious does not mean that it is credible. The first line of defense should always involve a careful dissection of the asserted patent claim to determine whether each and every element of that claim is present in the accused device or method. Absence of even a single claimed element means that the infringement accusation is unsubstantiated. As patent attorneys, we often encounter intimidating cease and desist letters alleging patent infringement when there is none. Accordingly, it is critical to perform an independent non-infringement analysis to determine whether the patent owner is standing on a solid ground or simply being a bully.