We explore how principles predicting the success of a medical information commons advantaged or disadvantaged three MIC initiatives in three Canadian provinces. Our MIC case examples demonstrate that practices and policies to promote access to and use of health information can help improve individual healthcare and inform a learning health system. MICs were constrained by heterogenous health information protection laws across jurisdictions and risk-averse institutional cultures. A networked approach to MICs would unlock even more potential for national and international data (...) collaborations to improve health and healthcare. (shrink)