Imagine that we are considering whether our healthcare system (or insurer) should fund treatment or procedure X. One factor that may be cited is that of so-called 'medical necessity'. The claim would be that treatment X should be eligible for funding if it is medically necessary, but ineligible if this does not apply. Similarly, (and relevant to the debates in this special issue), if considering whether a particular treatment should be ethically and/or legally permitted, we may wish to distinguish between cases where the treatment is medically necessary, and those were it is not. But what do we mean by this concept? Here I will propose and briefly defend one plausible and practical definition.
I introduce a distinction between health need and medical need, and raise several questions about their interaction. Health needs are needs that relate directly to our health condition. Medical needs are needs which bear some relation to medical institutions or processes. I suggest that the question of whether medical insurance or public care should cover medical needs, health needs, or only needs which fit both categories is a political question that cannot be resolved definitionally. I also argue against an overly strict definition of medical need on the grounds that this presupposes, wrongly, that medical intervention should always be a last resort.

