Just wanted to gather your insight. When you have a client/customer terminate a contract or choose not to renew their contract, is it best practice to hide any live case study documents/videos they were the focus of? Or is it okay to keep them live?
This kind of question -- and it's a good one -- is why any PR relationship with a client should have a separate contract, methinks.
The contract need not be long, but it should be clear about whether you can continue to name them in perpetuity no matter what; until they issue a specific takedown notice; until you've stopped working with them due to a "dishonorable discharge"; or until you've stopped doing business with them for any reason. (Obviously the best thing for you would be the one where they have to issue a takedown.)
In the absence of a contract, let's face it, most people leave their case studies and testimonials up even if they fired/were fired by the client, unless they want to deprive the client of the collateral benefits. Ask yourself whether the case study might lead to more questions than you'd like (somebody sees the case study, asks the client about you, they end up maligning you).
+1 on Sanford.
I would add that it is also possible that the PR part of the contract states that the case study does not expire when the license / service contract does.
Also, ask yourself if the existence of the CS might encourage your prospects to want to talk to your forme client, for instance if they happen to know each other. In the era of social networks, this, form my experiences, happens quite often.