Katharine converted to law after obtaining a BA (Hons) in English Literature and Language at Oxford University. She completed her law studies at City University and BPP in London. In 2005, Katharine qualified as a solicitor at Norton Rose Fulbright, where she worked as a dispute resolution lawyer until 2006. In 2007, Katharine obtained an LL.M (summa cum laude) in International Human Rights and Criminal Justice at Utrecht University. After a period working at the International Criminal Court and International Criminal Tribunal for the former Yugoslavia, Katharine defended her PhD (cum laude) in October 2015 at Utrecht University. Her PhD examined the accountability of armed groups under human rights law.