There are at least two known meanings:

1. A licence to kill can be defined as an official sanction by a government or government agency to a particular operative or employee to initiate the use of deadly force, presumably in furtherance of the government’s aims or policies, or in carrying out the operative’s assigned missions and presumably in an assassination or covert context rather than in an overtly military context.
2. It is sometimes used when referring to assisted suicide, or discontinuance of life support, especially by editorialists, who may use the phrase, possibly pejoratively, in reference to government sanction of either action.

While the idea of a licence to kill is popularly known from the James Bond novels and films, and has been used at least once by a headline writer, in reality, the legitimacy of deadly force usage from country to country is generally controlled by statute law, particular and direct executive orders, the common law, or military rules of engagement. In Britain, the Intelligence Services Act 1994 authorizes the secretary of state to grant immunity from British prosecution to personnel when they engage in any acts abroad that would be illegal under British law – such as murder.