About the Author: Mr. Sheerin is a California licensed patent attorney having represented clients accused of patent infringement in Federal District Court as well as through Inter Partes Review (IPR) at the US Patent Office. A few of Mr. Sheerin's recent results may be viewed here:

An accused infringer must file an IPR petition within12 months after an infringement lawsuit has been filed in district court (or lose the right to file). A big patent law firm might suggest waiting until the end of the 12 month window before filing the IPR petition in order to flush out all of the potential defenses the patent owner might assert against invalidity arguments. This might be a good strategy if the accused infringer is a large corporations with unlimited resources to burn on patent litigation. However if you are a smaller company, filing the IPR petition early in the 12 month window can help minimize the litigation expense.

After a patent infringement lawsuit has been filed, you might first consider filing a motion to dismiss the lawsuit by arguing the patent covers ineligible subject matter under 35 USC § 101, particularly if the patent involves software.

Assuming a motion to dismiss under 35 USC § 101 is not an option (or the motion is denied), the next step should be to perform an extensive prior art search for use in filing an IPR petition. Whether arguing invalidity to the district court or the Patent Trial and Appeal Board (PTAB), searching the prior art is the most critical part of patent litigation. When a patent application is initially examined, the patent examiner typically performs a very limited prior art search due to the time constraint imposed by their quota of patent applications they must process each month. It would be unreasonable to burden the patent examiners with an extensive prior art search given the tiny percentage of issued patents that are actually litigated. Therefore, even though a patent application makes it through the initial examination process, there is very likely additional prior art not considered by the examiner that can be used as the basis of an IPR petition, as well as used to induce a favorable settlement.

Searching the prior art takes a very particular skill honed by the best patent attorneys over years of practice. Engineers employed by search services are typically ill qualified for the task, either because they are not technically competent (otherwise they would be working as an engineer), or because they are not trained in the nuances of patent claims. Whatever the reason, my experience with search services is they are almost completely worthless. Again, the best prior art searches are performed by the best patent attorneys since this is the most important skill they bring to the table, which makes sense because the prior art search is the most important aspect of patent law litigation. When looking to hire a law firm to defend a patent infringement claim, I recommend interviewing multiple firms and then selecting the firm capable of performing the most competent prior art search, which means having a complete understanding of the technology, the invention, and the prior art. You could even request each law firm perform a prior art search for free as part of the interview process, and then select the law firm that finds the most relevant prior art (i.e., make them earn your business).