This article is a personal reflection on work as a physician with work as a member of the UK Parliament's House of Lords. Ethical thinking should underpin everything we do; the 'four principles' of medical ethics provide an applicable and relevant ethical framework. This article explores its application in both domains of work-as a clinician and as a legislator-with some examples of its use 'to do good medical ethics' in both roles. Debates around tobacco and drug control, pandemic control, abortion and assisted suicide are explored. Finlay IG.