1. A democratic ethical principle that official judgements and reports should be based on objective and relevant criteria, without bias or prejudice, and not take sides (as opposed to being partial; see also neutrality; political bias). Impartiality involves treating everyone as an equal rather than necessarily treating them in exactly the same way since it has been argued that sometimes individuals may be objectively judged to require different treatment. See also objectivity.
2. (journalism) An umbrella term for a cluster of associated concepts in professional ethics. In broadcast journalism these are reflected in editorial policies such as the need for programmes to reflect a wide range of views and opinions, to avoid bias or an imbalance of views on controversial issues (see also balance), and, where a single view is expressed, to avoid misrepresenting opposing views and allow a right of reply. This particular list is adapted from the BBC's editorial guidelines.
http://news.bbc.co.uk/1/shared/bsp/hi/pdfs/18_06_07impartialitybbc.pdf Safeguarding impartiality in the 21st century