Northern Ireland is used as a case study internationally, from how to deal with terrorism to initiating peace processes. Internment was the first state action of the Troubles that was conducted throughout the whole of Northern Ireland. The general consensus surrounding internment is that it was a failure. But, was it ethical? Were there some “good” elements to internment? What specific parts of internment should the UK tell other states to avoid? Or was the whole practice, from start to finish, unethical? This article attempts to make these lessons clearer by analysing internment through an ethical lens. To do so, it uses the Just Intelligence framework proposed by Mark Phythian and David Omand. It argues that overall, internment was unethical. Whilst internment was properly authorised, it is mostly unethical because it was not proportionate, it was not necessary in the rural areas, it failed to discriminate, the intention behind it was dubious and it was ultimately unsuccessful. Internment exacerbated the conflict by fuelling the PIRA with recruits; shifted the conflict from being urban-based to a nationwide conflict; alienated Nationalists against the security services; and tarnished the local and global reputation of the UK government.