The force of law

Afghanistan's police, often themselves the target of armed attacks, are officially authorised to respond with weapons "and explosives,” albeit only after other methods have failed, and no fewer than six warnings have been issued.

On the other hand, Mexican officers, pictured above, and Indian riot police both follow a defined escalation protocol that goes from verbal warnings to physical constraint, tear gas, water cannon or pepper spray, rubber bullets or baton rounds, and then use of firearms.

Many countries spell out that any use of firearms by police is a last resort, though this can be defined in many ways.

Britain, Bosnia, Serbia and the Philippines allow guns to be fired only if the life of the police officer or another person is under threat.

Many West European countries, meanwhile, allow firearms to be used "where necessary" to detain suspects or to prevent a serious crime.

Security guards at U.N. buildings in Geneva are not subject to Swiss law but still conform to local police rules. These rules, like those governing police in Italy, Austria, Belgium and Bosnia, specify that the use of force must be "proportionate".

In Malaysia, the Federal Reserve Unit, the main riot control is permitted to use firearms only in cases where the protesters are using them, but it is in a fortunate position.

The force's deputy superintendent, Kulwant Singh, says that "firearms have not been used in the 59 years since the FRU was formed".