I wanted to find out if the break-the-glass method is really needed where an emergency physician would use it to access a patient's electronic health record in the event of an emergency. Since an emergency physician would be treating patients that are not theirs, this would result in the emergency physician using the break-the-glass method the majority of the time unless the patient being treated has been treated by the physician in a non-emergency situation such as a GP visit. On the other hand, the break-the-glass method should not be over used, but it seems that it would be overused in an emergency situation and so this is why I am asking if it is really necessary in an emergency situation.
I think there is a misunderstanding of the circumstances to which "break the glass" applies, or perhaps the rules by which physicians nurses and other patient care professionals are granted access to patient records.
Regarding accessing the chart in general, annual training is given to physicians and hospital staff on the laws and regulations (for example under HIPAA, the Health Insurance Portability and Accountability Act) that no one is allowed to even open a patient chart without specific reasons for doing so - such as direct patient care or billing. These rules are a professionalism expectation, and any EMR (electronic medical record) keeps a record of access that can be traced. Additionally, EMR can restrict who can view what. For example, in one of the most prevalent EMRs called EPIC, the interface differs between users' job roles such that access to some areas in the chart is not even available for some users.
Within the US medical system EMRs, "Break the Glass" is a mechanism within the EMR chart where it requires a two-step process (justification and signature) to view certain data in a chart, or other circumstances such as open a chart of a patient who has died. For most physician access, it is most commonly used when accessing any psychology or psychiatry notes; in that case one justification selection is "for direct patient care." However, note that psychiatric meds will still appear in the medications list, and psychiatric diagnoses will appear in the problems list.
It is assumed that a physician or nurse will only open a chart for whom they are participating in care, thus an ER physician will have full access to the EMR chart for a patient they are taking care of, and would only need to do the "break the glass" procedure to gain access to psych notes - and would only do so if it is pertinent to the visit.
When a patient registers to be seen at an ER, some of this is explained in the terms of treatment paperwork that they have to sign. An unconscious patient situation has unique laws and regulations that apply, including assumed consent for chart access for reasons of health and life preservation.
Don't assume, however, that EMR between institutions communicate with each other. The technology to do so, although it's been possible since the 1980s, has not been implemented between most healthcare organizations. Even within the same city, they still don't often interface. If you go to a new hospital, they likely have access to zero medical information on you. This can be a significant barrier to continuity of care.
Some information on HIPAA and its application to EMR: