• It must be know that in Hong Kong, there exists no legislative laws governing a health directive. Any legal meaning is based on common law. It is unlike many states in the USA which has written laws on health directive. 
• It represents the maker's wishes on his or her health treatment in emergency
• It lets your physician, family, and friends know your health care preferences, including the types of special treatment you want or don't want at the end of life, your desire for diagnostic testing, surgical procedures, cardiopulmonary resuscitation and organ donation.
• Typically, it allows the authorized individual to make healthcare decisions when the patient becomes incapable.

It depends.

People consider a health directive together with a will and an enduring power of attorney (EPA) to supplement a health directive. It is commonly called as "three treasures of well-being": a will, a EPA and a health directive.

 An EPA enables the maker to make financial (health directive is on health decisions) decisions when the patient becomes incapable.

Consult your doctor and your lawyer on what you want to make. You can choose which documents to create, depending on how you want decisions to be made.

To make a health directive, you will have to consult a doctor who, as a witness, is required to explain the health directive to you. You may have to pay the doctors for the services rendered. According to the Hospital Authority, 2 witnesses are required and one has to be a doctor.

It does not require a solicitor to witness unless you choose to do so. The enduring power of attorney would however require a doctor and a solicitor to witness signing.

Yes. 

The usual method to revoke, modify or cancel a health directive is by way of destroying the document, write on it indicating its revocation or cancellation properly witnessed. Modification can be done by replacing it with a new one.

• a patient may make decisions on his or her health treatment in "advance" when he or she is still capable of making the decision. Therefore, in the United States, it is often called "advanced health directive" .
• It enables the patient's family members to make decisions on medical treatment easier when emergency arises.
• In Hong Kong, the scope of a health directive is limited by the official guidelines released by the Hospital Authority. Please refer to the following FAQ for answer.

A health directive takes effect at times of losing your mental capacity.

According to the Hospital Authority, It will take effect when the patient has lost decision-making capacity under the three prescribed conditions. These conditions have to be certified by two doctors.

1. terminally ill; 
2. persistent vegetative state; and 
3. other end-stage irreversible life limiting conditions.

For the purpose of condition no.3 above, "Other end-stage irreversible life-limiting conditions" include :

• (i) end-stage renal failure, end-stage motor neuron disease, and end-stage chronic obstructive pulmonary disease which do not fall into the category "terminally ill" because life can be prolonged by dialysis or assisted ventilation; and 
• (ii) irreversible loss of major cerebral function and extremely poor functional status. 

You need to find an experienced doctor. Lawyers at Yip Tse & Tang may refer a suitable doctor for you.

There are standard procedure or formalities that you have to go through and there are standard forms for the purpose.

The first thing is to understand your needs and find a doctor experienced in this aspect. The doctor will prepare the health directive for to and to act as your witnesses. The doctor will make sure you understand all your options, what the health directive means, and that it meets all the good medical practices. 

Basically, the doctor should be satisfied that the patient is mentally competent and well-informed of the decisions made in the health directive

On our experience, this is usually done within few days. In emergency cases, it may be done in shorter period of time.

The following is taken from a paper prepared by the Research Office Information Services Division Legislative Council Secretariat dated 6 June 2019 titled "Advance healthcare directives of patients" .

Existing implementation framework: While there is no dedicated legislation on ADs in Hong Kong at present, instructions of patients made in ADs are recognized under common law. 

To facilitate implementation, Hospital Authority (HA) issued a standard form for ADs in July 2010 for local adults to fill in, along with a detailed guideline for HA clinicians.Here is the implementation gist:

(a) Refusal of life-sustaining treatments: In the standard form, patients can opt to refuse certain life-sustaining treatments (e.g. CPR, artificial ventilation and artificial nutrition)

A shorter AD form containing only the refusal of cardiopulmonary resuscitation ("CPR"), a common and invasive life-sustaining treatment, was introduced in 2014 to "help reducing the psychological stress that may arise from signing the more complex full AD form" under three prescribed conditions, namely 

(i) terminally ill; 

(ii) persistent vegetative state; and 

(iii) other end-stage irreversible life limiting conditions; "Other end-stage irreversible life-limiting conditions" include (i) end-stage renal failure, end-stage motor neuron disease, and end-stage chronic obstructive pulmonary disease which do not fall into the category "terminally ill" because life can be prolonged by dialysis or assisted ventilation; and (ii) irreversible loss of major cerebral function and extremely poor functional status. 

(b) Signatures of two witnesses including a doctor: The AD form requires signatures of two witnesses, one of whom must be a registered doctor who should be satisfied that the patient is mentally competent and well-informed of the decisions made in the AD. If this doctor works in HA, this creates an opportunity for discussion of ADs and end-of-life care with patients and their families;  The Hospital Authority ("HA") revised its Guidelines on Life-sustaining Treatment in the Terminally Ill to include the concept of advance care planning to engage patients and their families in discussion of end-of-life decisions in 2015. 

(c) ADs taking effect at times of losing mental capacity: The AD will take effect when the patient has lost decision-making capacity under the three prescribed conditions discussed above. These conditions have to be certified by two doctors; and

(d) Applicability of ADs witnessed by non-HA doctors: For those ADs witnessed by an HA doctor, they are filed by HA for cross-checking when in need. However, for ADs made outside HA, their validity may be prone to challenge from HA doctors. If family members of patients cast doubt on ADs, the treating doctors also need to carry on life-sustaining treatment while awaiting clarification.