This article considers intervention in proceedings about withholding and withdrawing life-sustaining medical treatment. Since the early 1990s, there have been a number of important decisions, both in Australia and overseas, about whether life-sustaining treatment should be withheld or withdrawn from an adult who no longer has capacity to make the decision for himself or herself. In almost all of these decisions, intervention by a non-party to the matter has been an issue. This article explores the rules of intervention in applications to appear as a party and as amicus curiae, and considers those rules in the context of decisions to withhold and withdraw life-sustaining medical treatment. The relevant cases are examined as are the advantages and disadvantages of intervention in these circumstances. The article concludes by suggesting a model for intervention that strikes the appropriate balance between ensuring all relevant issues are placed before the court while still respecting the intensely private nature of a decision to withhold or withdraw a life-sustaining measure in any given case
