The Code requires that if any class is impaired under a Chapter 11 plan, the plan cannot be confirmed unless at least one impaired class accepts the plan (determined without including any acceptances of the plan by insiders). This can be the most difficult of the plan confirmation requirements for a debtor to satisfy, especially in a single asset case, because unlike other obstacles to confirmation, such as rejection of the plan by a creditor class, “cramdown” is not available as an end run around this requirement.
Bankruptcy Code § 1129(a)(10). See also Artificial Impairment, Confirmation Requirements, Gerrymandering, Non-Impairment Plan.