This thesis seeks to assess the factors which affect the judicial behaviour of the Chilean and Argentinean supreme courts in freedom of expression cases. The freedom of expression has many facets, but here the focus is on defamation (or "insult" laws) and prior censorship. Chile is unique is this respect; it has more contempt of authority provisions than any other state in the hemisphere. In both countries, the freedom of expression is formally protected in accordance with international obligations, but the judiciaries seem reluctant to give precedence to constitutional principles of freedom of expression over national legislation. The question asked is therefore which factors influence the courts' protection of freedom of expression?