hospice nursing perspective

I am in my last semester of school, doing some work on the ethical issues surrounding "futile care." Realizing that by the time hospice enters into a terminally ill patient's care, there has been some agreement reached among patient and family as to realistic treatment options, I'm interested in hospice nurses' views on involvement by doctors in hospice care. I know that the doctors directly involved (ie: medical directors) are extremely supportive but what are your experiences with MD's who are more reluctant to "let go" of life-prolonging treatments in accordance with patient wishes? What do you see as the reasoning behind this? Fear of legal repercussion? Ego?

Any info is greatly appreciated.

Meegan