We are not suggesting that one case in itself should determine the fate of Chevron deference, but if there were one, the following is most certainly an excellent candidate.
A plaintiff seeks relief in the court claiming that the agency had no authority to issue a rule. 340B Complaint
The Court opines in no uncertain terms that the agency does not have the authority to issue the rule. See 340B order
The agency responds by issuing an interpretative rule which renders moot the decision of the court. http://www.hrsa.gov/opa/programrequirements/interpretiverule/interpretiverule.pdf
The FR notice announcing the availability of the rule is here: https://www.federalregister.gov/articles/2014/07/23/2014-17409/availability-of-interpretive-rule-implementation-of-the-exclusion-of-orphan-drugs-for-certain
The counter argument is that when the agency issued “guidance” it is not binding upon interested parties. However in this instance the “guidance” of interest deals with securing favorable financing from a federal agency and failure to comply will form the basis for the rejection of such requests.
The blatant refusal of an agency to comply with an order of the court hardly makes the case for Chevron deference.