After re-reading jack w's initial post on the topic, I feel quite strongly that an ethical breach has occurred in this situation:
one of her nurses is a witness, and knew that she was one as well. The nurse checked her records, and saw that she had signed the statement. The nurse then came into her room and said "Did you know that you signed a statement stating you WOULD accept a blood transfusion?" She lied and said that she was signing so many papers when she got in that she must have made a mistake by signing it, and that it certainly wasn't her intention to do so. The nurse scolded her and told her how that could have created a huge problem for her, and the 'patient' said she would have to take care of it.
The instant the RN used her position as a nurse to cross the line and approach this patient in her capacity as a JW, she went beyond her duties as a nurse and the ethics she is bound to uphold from a professional standpoint.
The nurse is supposed to deal with a patient in a way that fosters trust (or fidelity), and immediately upon confronting the patient in this manner, the result was that the patient had to come up with a lie to cover for herself. The unprofessional behaviour of the nurse provoked distrust in those providing her care at that very moment.
In addition, the nurse scolding the patient and telling the patient about the potential for creating a "huge problem for [the nurse]", is not the patient's problem, and it imposes an unfair burden on the patient to be coerced into a situation not of her choosing. Her autonomy as a patient has been compromised.
The other ethical principles involved are non-malfeasance and beneficence which go hand in hand: the duty to remove or prevent harm from coming to the patient and the duty to take positive action for the patient's benefit. To the JW mindset, the nurse may have rationalized that approaching the patient the way she did was for the greater good of the patient and the congregation (and ultimately for herself). However, in a non-life-threatening situation, (as this was at that particular moment) it is not for the nurse to decide where the harm or benefit lies in the decision making process. The decision on harm vs benefit is the patient's to bear - and the nurse must respect the patient's autonomy in that decision making process, without coercing an opposite decision to be made.
This is an extremely good example of why - if you are willing to accept blood transfusions or blood products - you must expunge any reference to being or having been a JW from all your medical records. Never disclose any JW affiliation on any hospital intake interview, and make sure you discuss with your physician that NO JW staff members are to be involved in your care while in hospital. You do not want them to be anywhere near your charts.
I wouldn't trust a JW with my medical information if my life depended on it.