Some governments release detailed data on capital punishment, while others release nothing at all.
Cornell Law School Center on the Death Penalty Worldwide hosts data on global executions.
The Political Terror Scale assesses the human rights situation on a yearly basis in a large number of countries. The Scale codes information concerning extrajudicial executions, torture, political imprisonment, and exile.
The Death Penalty Information Center hosts a searchable database of executions carried out in the United States.
Data on extrajudicial executions has been collected by human rights organizations using data from household censuses and random sampling. See the work of the Human Rights Data Analysis Group for examples in this space.