A medical ethicist is also sometimes called a clinical ethicist or bioethicist. These are healthcare professionals with either a PhD or MD/DO and advanced fellowship training who specialize in helping patients, families, and medical teams solve medical ethics dilemmas. They also commonly work with medical teams who use high-tech therapies such as organ transplantation and deep brain stimulation.
A medical ethicist is not the same as an ethics committee. An ethics committee is a group of hospital volunteers from a variety of backgrounds (e.g., social work, nursing, psychology, pastoral care, medicine) who meet usually monthly to work on ethical problems/issues in the hospital setting. The members generally have very basic ethics training (e.g., a few seminars, workshops). Sometimes a professional medical ethicist is a member of an ethics committee but not always. Generally, large, academic medical centers employ professional medical ethicists; whereas community hospitals rely solely on their ethics committee for handling ethical dilemmas. Professional ethicists are also available in the community in private practice (e.g., www.AskTheEthicist.com).
Patients, families and medical teams can request an ethics consultation whenever they need help with moral distress or ethical decision-making. You can learn more about the role of a medical ethicist in my book, Finding Your Way: A Medical Ethics Handbook for Patients and Families.