Let's say that the computer is only located in the nursing station, not patient rooms, hallways, alcoves, etc etc since this is 2015 and computers are now beyond the nurse's station in any reputable, updated hospital setting. Let's not forget that iPads and tablets are coming into use and those defintely go out of the nurse's station. OK, so let's say ALL computers are ONLY in the nurse's station because its 1999. Are nurses the only people in that area? NO!! Housekeeping, maintenance and others are in the area and have NO business reading patient medical records. Actually, other nurses have NO BUSINESS reading the medical records of patients that they are not caring for.
In short, it is a big violation of the information security agreements of many hospitals, not to mention HIPAA, to leave the EMR open and walk away. I usually log out the careless nurse and have a discussion with him/her about it. They've always appreciated it and so do I. We all make mistakes, let's not minimize our impact as a guardian of a patient's privacy.