Quinn Emanuel and McDermott Breaches Turn Data Security into a Relationship Test

On September 3, 2026, Reuters reported that Quinn Emanuel and McDermott had disclosed separate data breaches involving social-engineering access, with Quinn saying a limited number of client documents were affected and McDermott reporting exposure involving Social Security numbers and health data. The firms said the incidents were limited and addressed, while the report noted several other major firms had recently disclosed breaches. For client teams, incident response now affects retention directly: buyers will judge notification speed, clarity, ownership and evidence of remediation alongside technical containment. Relationship leaders should know the client-facing breach protocol before an incident occurs and ensure security commitments made in pitches and outside-counsel guidelines can be demonstrated in practice.