International Conference of Rome for the Social Defense Against Anarchists

The other resolutions drafted in the final protocol included the introduction of legislation in the participating governments to prohibit the illegitimate possession and use of explosives, membership in anarchist organizations, the distribution of anarchist propaganda, and the rendering of assistance to anarchists. It was also agreed that governments should try to limit press coverage of anarchist activities and that the death penalty should be mandatory punishment for all assassinations of heads of state.

The authorities used the opportunity to organize an international system of exchange among the national police agencies, using the portrait parlé method of criminal identification. This was developed from the bertillonage system invented by Alphonse Bertillon and involved the classification of criminal suspects on the basis of numerically expressed measurements of parts of their head and body.

A further anti-anarchist conference was held in Saint Petersburg in March 1904. This conference was called after an anarchist assassinated William McKinley, the President of the United States, on 14 September 1901. Ten governments sent representatives, including Germany, Austria-Hungary, and Denmark.

Here, the Secret Protocol for the International War on Anarchism was drawn up. Portugal and Spain were to subsequently agree to this, while France and Great Britain decided not sign the St. Petersburg Protocol, but did express a willingness to help other states on police matters relating to anarchism. The United States government neither participated in the St. Petersburg meeting nor agreed to follow its provisions. However, President Theodore Roosevelt, McKinley's successor, had called for an international treaty to combat anarchism.

The conference has been identified as the first international conference against terrorism.