In the year following his graduation Blackburn was elected to a fellowship at Trinity College, but at this stage his intention was to follow a career in the law and he was admitted at the Inner Temple on 2 November 1847.
Sa mga sumusunod na mga taon ng kaniyang pagtatapos Blackburn ay elected sa isang relasyon at Trinity College, ngunit sa hakbang na ito ang kanyang intensyon ay upang sundin ng isang karera sa batas at siya ay natanggap sa loob ng Templo sa 2 Nobyembre 1847.