Western Sugar Coop. v. Archer-Daniels-Midland Co.

Beyond the concurrent-conflict issue with Tate & Lyle, the merged law firm had also previously represented co-defendant Ingredion, advising it on the legality of its high-fructose-corn-syrup advertising from 2004 until 2013; that representation had formally ended under the terms of its engagement before the merger, but the current false-advertising suit against Ingredion concerned precisely the advertising practices the firm had once advised on. Ingredion, alongside Tate & Lyle, moved to disqualify the firm from continuing to represent the sugar-industry plaintiffs.

Whether a lawyer seeking to represent a client adverse to a former client, without obtaining informed consent, may be disqualified upon the former client's showing of a substantial relationship between the subjects of the prior and current representations.