On September 6, 2016, in Arrigo v. Link Stop, Inc., the US Court of Appeals for the Seventh Circuit recently joined other circuits in holding that a trial court's denial of a motion to amend constitutes a decision on the merits for res judicata purposes ( (7th Cir. Sept. 6, 2016)).

Plaintiff Marylee Arrigo's employer terminated her employment, and Arrigo filed suit in the US District Court for the Western District of Wisconsin. In her complaint, Arrigo alleged that she was fired for taking leave under the federal Family and Medical Leave Act (FMLA). Six months after filing suit, Arrigo filed a motion for leave to amend her complaint to add pregnancy and disability claims under Title VII and the Americans with Disabilities Act (ADA). The district court denied Arrigo's motion for leave, finding that Arrigo's motion was untimely and would have unfairly prejudiced the defendant.

Following the district court's denial of her motion for leave, Arrigo filed a second federal lawsuit in which she alleged the same Title VII and ADA claims. The district court subsequently granted defendants' motion to dismiss the second lawsuit.

Arrigo's original case proceeded to trial on the FMLA claim, and the jury found in favor of the defendants. Arrigo then appealed multiple district court decisions, including the district court's dismissal of her second lawsuit, arguing that the district court should not have dismissed her second lawsuit on res judicata grounds.

The doctrine of res judicata bars claims that were litigated (or could have been litigated) in a previous proceeding when there was a final judgment on the merits. On appeal, Arrigo contended that the district court's denial of her motion for leave (through which she sought to incorporate the Title VII and ADA claims in her initial suit) did not constitute a final judgment on the merits. The Seventh Circuit disagreed.

Consistent with its recent decision in Bell v. Taylor, (7th Cir. July 1, 2016) and prior rulings by the US Courts of Appeals for the First, Third, Eighth, and Eleventh Circuits, the Seventh Circuit held that the district court's denial of Arrigo's motion for leave to amend constituted a final decision on the merits for the Title VII and ADA claims that Arrigo sought to assert. The Seventh Circuit reasoned that ruling otherwise would: