You violated no shipping rules, the cds arrived in good condition, so you don't owe her a credit.  Using cd cases isn't even a requirement for shipping, it's a suggestion. 

If the CD's are operable, I certainly wouldn't refund her credit.  It doesn't appear as if you're under any obligation to do so.

Thank you for your comments! I appreciate the help!

I also agree.  Original container is not required for CD's and therefore the fact that yours arrived damaged is irrelevant for the purposes of RWAP and credit returns.  Unless the CD's arrived damaged, then there might be grounds to consider if the package was wrapped securely. 

For myself, I probably wouldn't mail a jewel case with only a bit of paper for protection, they are brittle and break easily.  Those plastic DVD cases are a bit more flexible and less prone to damage.  I'd probably find a small box to pack a jewel case in.

I agree with Denise-- the jewel cases are easily cracked, even when they aren't going thru the mail!  I have bought several thru Amazon vendors who didn't use bubble wrap and the cases arrived cracked so it does seem that without the protective wrap it is very likely damage could occur.  but no, I don't feel you truly "owe" them a credit for that, but I would change how I mail them in the future.

We put bubble wrap around the case but do not mail them in a box unless quantity dictates. As was already stated, the case is not even required to be sent. We send the case for the safety of the cds and have received and sent broken cases. Never have I complained or received a complaint when the case was broken. Sorry it happened to you but you did nothing wrong.

I use bubble envelope mailers for mine, or wrap them in bubble wrap.

If USPS breaks them after that, I figure it's just circumstance. 

Jewel cases are like 10 cents at my local thrift store.  Not exactly a credit.  :)