After a district court in the Eastern District of Virginia invalidated the patent-in-suit because it did "not pass the two part test laid out by the Supreme Court in Mayo and Alice." Peschke Map Techs. LLC v. Rouse Properties Inc., No. 1:15-cv-1365, --- F. Supp. 3d ----, 2016 WL 1031295, at *7 (E.D. Va. Mar. 8, 2016), the plaintiff moved to dismiss a patent infringement action pending in a different district while a motion for judgment on the pleadings was pending.

The defendant had moved for judgment on the pleadings in its favor, arguing it cannot infringe on an invalid patent and that plaintiff is collaterally estopped from continuing to pursue its infringement claim. As noted by the district court, it is well known that a patentee is estopped from pursuing infringement claims for a patent that has been invalidated by another federal court, even if that action involved a different defendant. See Blonder-Tongue Labs., Inc. v. Univ. of Illinois Found., 402 U.S. 313, 333 (1971).

The district court then noted that the plaintiff did not address collateral estoppel in its response to the motion, but instead argued, "without any support, that this issue is moot because there is a pending motion to voluntarily dismiss the infringement claims."

The district court disagreed that the motion was moot. "There are two categories of voluntary dismissals - those that need court approval and those that do not. The former involves either a voluntary dismissal before the defendant files an answer or a motion for summary judgment, or a voluntary dismissal that the parties have signed and stipulated to. Fed. R. Civ. P. 41(a)(1). These types of dismissals are effective upon filing and require no further action by the Court. See Anago Franchising, Inc. v. Shaz, LLC, 677 F.3d 1272, 1278 (11th Cir. 2012). Any other attempt to voluntarily dismiss an action falls into the latter category and requires court approval, on terms that the court considers proper. Fed. R. Civ. P. 41(a)(2)."

The district court then noted: The Court enjoys broad discretion in determining whether dismissal pursuant to Rule 41(a)(2) is appropriate. See Pontenberg v. Boston Scientific Corp., 252 F.3d 1253, 1255 (11th Cir. 2001). This discretion is not unfettered, however. The Eleventh Circuit has explained, "[i]n most cases, a voluntary dismissal should be granted unless the defendant will suffer clear legal prejudice, other than the mere prospect of a subsequent lawsuit, as a result." Id. (citation omitted). The key question, then, is whether the defendant would "lose any substantial right by the dismissal." Id. Turning to this action, the Court finds Defendant may suffer such a loss if Plaintiff's voluntary dismissal was granted over Defendant's objection.

Because a court may award reasonable attorney fees to the prevailing party of an "exceptional" patent case. See 35 U.S.C. § 28, the district court found that a Rule 41(a)(2) dismissal might cause defendant to lose a substantial right--its status as the prevailing party under 35 U.S.C. § 285.

As a result, the district court denied the plaintiff's request to dismiss and granted the defendant's motion for judgment on the pleadings.

Peschke Map Technologies LLC v. Miromar Development Corp., Case No. 2:15-cv-173-FtM-38MRM (M.D. Fla. Apr. 15, 2016)