Before the Al Qaeda attacks in the us, it was hard to find support for torture in the liberal-democratic world. However, post 9/11 torture (or at least something very close to torture) was used by liberal democracies like the United States (us). Practices like water-boarding were justified by reference to the war on terror. Underneath this lies a reasoning that we have two options, some large scale act of violence and torture, and that torture is a lesser evil, exemplified by ‘ticking time bomb’ scenarios – if you have two options, both bad, but one is far worse than the other, the lesser evil seems a reasonable decision. This article proposes that there is a moral danger through slippage from recognising torture as a generally justified action. It explains this slippage by reference to the ‘halo effect’: a cognitive bias in which something is judged as permissible or good through association with non-relevant facts. Given the current risks of domestic terrorism, the article argues that we need to learn from the us example post 9/11 to ensure that we avoid justifying uses of torture in non-exceptional circumstances.