755 ILCS 43/45: Principal's wishes must be followed.

(1) The physician or provider may subject the principal to mental health treatment in a manner contrary to the principal's wishes as expressed in a declaration for mental health treatment only:

(a) When a court order contradicts the principal's wishes as specified in the declaration; or

(b) In cases of emergency endangering life or health.

(2) A declaration does not limit any authority provided in Sections 3-100 through 3-910 of the Mental Health and Developmental Disabilities Code either to take a person into custody, or to admit, retain, or treat a person in a health care facility.