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:

If a defendant is a prevailing party in a district court case, they may be awarded attorney fees under 35 USC § 285 (e.g., based on substantively weak infringement argument, litigation misconduct, failing to preform a pre-suit infringement investigation, or fraud on the patent office). However, multiple district courts have held that such attorney fees do not include the fees incurred during an Inter Partes Review proceeding.

For example, an Ohio district court in Sherwood Sensing Sols. LLC v. Henny Penny Corp., 2022 U.S. Dist. LEXIS 90872, *1 (S.D. Ohio May 20, 2022), held that attorney fees are not available because they are outside the scope of 35 USC § 285. The Ohio district court relied on Federal Circuit dicta in Dragon Intell. Prop. LLC v. Dish Network LLC, 956 F.3d 1358 (Fed. Cir. 2020) which held that “we see no basis in the Patent Act for awarding fees under § 285 for work incurred in inter partes review proceedings that Appellants voluntarily undertook.”

Note that these are recent cases, and the Federal Circuit has yet to rule on this question directly (only in dicta). It is likely a party will appeal this question directly, in which case the Federal Circuit will likely issue a binding decision. I believe the "voluntary" dicta argument of Dragon Intell is particularly weak. No defendant "voluntarily" spends hundreds of thousands of dollars on an IPR. Almost every defendant is "forced" into challenging a patent in district court or the USPTO because the patent is being asserted offensively by the patent owner, for example, by cancelling Amazon listings or otherwise interfering with the defendant's business (e.g., through cease and desist letters sent to the defendant's customers or distributors).