Cal. Probate Code § 4657 : California Probate Code — Health Care Decisions — General Provisions — Patient presumed to have capacity Date: 31 Aug 2016 TEXT PDF Current through the 2016 Legislative Session A patient is presumed to have the capacity to make a health care decision, to give or revoke an advance health care directive, and to designate or disqualify a surrogate. This presumption is a presumption affecting the burden of proof. Ca. Prob. Code § 4657 EFFECTIVE 7/1/2000. Added October 10, 1999 (Bill Number: AB 891) (Chapter 658).