Members of the public write messages of condolence in chalk on the pavement near the site of the Sydney cafe siege in Martin Place, December 17, 2014. Tough new national security laws failed to prevent a deadly hostage crisis in the heart of Sydney this week, Australian Prime Minister Tony Abbott said on Wednesday, raising questions about the usefulness of such measures. REUTERS/Jason Reed (AUSTRALIA - Tags: CRIME LAW POLITICS CIVIL UNREST)