Baby Jogger v. Monahan Products, LLC d/b/a UPPAbaby, 1:24-cv-11582

Baby Jogger, LLC owns several patents related to convertible single-to-double strollers and alleges that UPPAbaby infringed these patents with its Vista stroller and RumbleSeat products.
In December 2015, Baby Jogger sent UPPAbaby a letter warning of potential patent infringement and followed up with further details; UPPAbaby responded, contesting infringement and the validity of the patent.
Baby Jogger replied to UPPAbaby’s rebuttals in March 2016 but took no further action until filing suit in June 2024, while UPPAbaby continued selling the accused products.
UPPAbaby moved for summary judgment, arguing that Baby Jogger’s claims were barred by equitable estoppel due to the eight-year period of inaction.
The dispute before the court was whether Baby Jogger’s lengthy inaction, coupled with the parties’ prior communications, constituted misleading conduct causing UPPAbaby to reasonably rely to its prejudice.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Equitable estoppel: misleading conduct	Inaction alone, amid continued communications, does not equal abandonment	Eight years of inaction led to belief of non-enforcement	Not enough as matter of law—triable issue
Equitable estoppel: reasonable reliance	UPPAbaby provided no evidence it relied on inaction	UPPAbaby relied on silence to invest in products	No sufficient proof of reliance

Scholle Corp. v. Blackhawk Molding Co., 133 F.3d 1469 (Fed. Cir. 1998) (sets out test for equitable estoppel in patent cases)
A.C. Aukerman Co. v. R.L. Chaides Constr. Co., 960 F.2d 1020 (Fed. Cir. 1992) (explains elements and application of equitable estoppel in patent litigation)
Aspex Eyewear Inc. v. Clariti Eyewear, Inc., 605 F.3d 1305 (Fed. Cir. 2010) (addresses how silence or inaction can be misleading in equitable estoppel)
Borges ex rel. S.M.B.W. v. Serrano-Isern, 605 F.3d 1 (1st Cir. 2010) (standard for summary judgment)