Thermo Fisher may have hit “send,” but the Ninth Circuit was not willing to call that “signed, sealed, delivered.” 

In an unpublished, nonprecedential memorandum, the Ninth Circuit affirmed the denial of Thermo Fisher's motion to compel arbitration, finding that California law requires notice and mutual assent, not just unopened emails and an expired opt-out period. (Rickes v. Thermo Fisher Scientific, Inc., et al., No. 25-5138 (9th Cir. Aug. 5, 2026)). 

The case arose from Scott Rickes’s California employment action against Thermo Fisher Scientific, Inc., in which he alleged age discrimination and related claims. Thermo Fisher moved to compel arbitration under its Mutual Dispute Resolution Agreement, which the company had distributed to employees by email in 2019. But the record showed only that Thermo Fisher sent Rickes four emails about the agreement; it did not show that he opened them, clicked the link, viewed the agreement, or otherwise interacted with the arbitration materials. Rickes also declared that he received a high volume of work emails, did not recall receiving the MDRA communications, and had never seen the agreement before the litigation. 

Reviewing the district court's denial de novo, the Ninth Circuit panel began with the foundational principle that "[t]he party seeking to compel arbitration bears the burden of proving the existence of an agreement to arbitrate by a preponderance of the evidence." Under California law, contract formation "requires both notice of the proposed agreement and mutual assent," and mutual assent "is determined objectively from the parties' outward manifestations."  

Critically, the court invoked its prior holding in Norcia v. Samsung Telecommunications America, LLC, that “California courts have . . . made clear that silence alone does not constitute assent.” The panel found that Thermo Fisher's electronic records “do not show that Rickes viewed the emails, clicked the hyperlink to the agreement, or otherwise interacted with the arbitration materials.”

Thermo Fisher argued that Rickes accepted the MDRA "by merely continuing his employment after failing to opt out within 45 days," but the court held that "under California law, that is not enough to establish mutual assent," citing Sellers v. JustAnswer LLC for the principle that assent in electronic transactions “is ordinarily inferred through affirmative conduct such as 'clicking buttons,' 'checking boxes,' or otherwise interacting with the contractual terms.”

In light of this decision, employers rolling out or maintaining electronic arbitration programs should ensure their systems capture evidence of affirmative employee engagement. Best practices include requiring employees to click through to the agreement and check a box acknowledging receipt, logging that interaction electronically, and following up with employees who have not completed the acknowledgment. Where feasible, employers may also consider obtaining a signed acknowledgment (whether wet ink or e-signature) confirming that the employee received, reviewed, and agreed to the arbitration terms. Simply sending an email with an embedded hyperlink and relying on a passive opt-out framework may leave employers without the evidentiary record needed to enforce arbitration if challenged.