As a developer, you will eventually come across a customer or user that will try to use you as a scapegoat. It is unfortunate that there are people like this but it is part of the job and is many times the reason we are forced to play the CYA game. You know the type. The code you wrote 7 years ago that has worked exactly as specified, went through User Acceptance Testing, and was QA'd is now suddenly "broken" because one new manager does not like the way it behaves.
You get the email/phone call that says there is a bug in your code and when can you have it fixed? This my friends is not the way to win friends and influence people. A much better approach would be to say "We have re-evaluated our business rules for the xyz application and we would like you to help us change the code to adhere to the new rules". For some reason there are still people out there that don't realize that you can attract more flies with honey than with vinegar.