As an IT, you have access to personal data. You should always get customer permission before copying or changing it.
Client confidentiality is the principle that an institution or individual should not reveal information about their clients to a third party without the consent of the client or a clear legal reason. This concept is commonly provided for in law in most countries.
The access to a client's data as provided by the institution in question is usually limited to law enforcement agencies and requires some legal procedures to be accomplished prior to such action (e.g.: …