Standard of Care - Set by Law, Not by Clinicians

In Cuthbertson v. Rasouli, the Appellants argue to the Supreme Court that physicians should not be required to provide treatment outside the standard of care, as the lower courts held the HCCA requires.  But this assumes that the standard of care is and can be determined independent from legal obligations under the HCCA.  This assumption appears to be rejected by the Health Professions Appeals and Review Board.  The Board seems to think that the standard of care applicable to an Ontario clinician is itself shaped and determined by legal obligations under the HCCA.