Many governments, civil society organizations, and international development agencies today seek to limit the use of pretrial detention in criminal justice. Motivations vary. Some believe that pretrial detention is ordered indiscriminately and employed for unreasonably long periods; others are concerned with the conditions of confinement and the burdens detention places on families; still others worry about the criminogenic effects of pretrial incarceration. But whatever the motive to limit the use of pretrial detention, it is difficult to imagine the effort succeeding without a good indicator of the extent of its use. Such an indicator has proven surprisingly elusive in countries at every income level. Indeed, it is possible that the effort to reduce pretrial detention in developing countries may actually be hindered by the indicator most commonly used there: the proportion of prison inmates on any given day that is not sentenced. This paper describes some of the flaws with this and other indicators, and shows how domestic governments and their development partners can use a basic and better indicator—the median duration of detention—as a catalyst for change. This paper demonstrates a simple and inexpensive way of developing this indicator – by obtaining administrative data already collected in most prisons and jails about the people who leave detention each month. Everywhere in the world, some number of detainees "exit" each month: some released to continue awaiting trial at liberty, others released at the end of their cases without a prison sentence, and still others whose pretrial detention has been changed to a sentence of incarceration following a criminal conviction. Virtually every prison and jail in the world records the dates of these "exits" whether they are actual releases or merely the reclassification of a pretrial detainee as a sentenced prisoner. Only these administrative data can generate an accurate measure of the duration of detention.
Foglesong, Todd, and Christopher Stone. "Prison Exit Samples as a Source for Indicators of Pretrial Detention." Indicators in Development: Safety and Justice Series, Program in Criminal Justice Policy and Management, Harvard Kennedy School, April 2011.