The case in question is a decision by the Ohio Supreme Court, State ex rel. Toledo Blade Co. v. Seneca County Board of Commissioners, 2008 WL 5157733 (Ohio Dec. 9, 2008). Plaintiff sought e-mails of county commissioners concerning demolition of an old courthouse. The county turned over some e-mails, but plaintiff managed to show that some relevant e-mails were missing because they had been deleted. It made this showing by analyzing the e-mails that were turned over and proving some logical gaps appeared within them. Also, some commissioners admitted they had deleted some of their relevant e-mails.
Ben Wright identifies an Ohio case where a misapplied email retention policy, and a lawsuit, forced an expensive effort to do forensic reconstruction of electronic mail to satisfy a FOIA request.