A major contributing factor to the lack of realized benefits with electronic health records in the United States is that the interoperability specification, CCDA, is only loosely complied with under the "meaningful use" rule from Health and Human Services. Certification is done on site at the EHR manufacturer, in an environment controlled by the manufacturer. The demonstration of compliance does not have to be done in a default "out of the box" environment, but merely that the system is _capable_ of being configured in a way that allows for emitting standards-compliant CCDA.

In practice, this means that most manufacturers do not build systems that are standards compliant by default, and definitely do not install systems that are standards compliant in their initial configuration. Then, individual healthcare practices add customization on top of that, which further complicates data integration.