This is why they say that the number one rule of pentesting is to get senior management approval in writing.
In his words: How a whitehat hacked a university and became an FBI target | Ars Technica
Basically, a guy who worked as a developer (for a company that had the University of Maryland as a client) realized that the university had some major security vulnerabilities that exposed a database full of SSNs and other PII. After he realized that his company wasn't planning to do anything about the vulnerability, this guy exploited it and posted some of the information, including the university president's SSN, to Reddit. Then the FBI kicked in his door...