Chapter 4 | Page 151 inadequate.51 By definition, total reserves comprise holdings of monetary gold, special drawing rights, reserves of the IMF members held by the IMF, and holdings of foreign exchange under the control of monetary authorities.52 Of these, foreign exchange reserves are held by central banks, usually in a foreign-denominated currency, as a measure of protection against global economic shocks. Although such protection is vital, the accumulation of large foreign exchange reserves represents idle resources for countries where resources are scarce.53 Thus, it is legitimate to question whether these reserves could be minimised through other means, such as better capital control policies, particularly those designed to limit the cross-border flow of speculative capital.54 This would free these resources for much-needed investment for the realisation of human rights.55 As a rule, many central banks maintain more reserves than the threemonth safety benchmark, which suggests that a significant amount of resources can be freed up for urgent expenditure. The non-tax revenue sources discussed above have the potential to make a significant contribution to the overall revenue stream of the State. The policy implications related to these sources of revenue from an ESC rights perspective are addressed in more detail later in the chapter. 51 See for example, Diane Elson, Radhika Balakrishnan and James Heintz, 'Public Finance, Maximum Available Resources and Human Rights' in Aoife Nolan, Rory O'Connell and Colin Harvey (eds), Human Rights and Public Finance: Budgets and the Promotion of Economic and Social Rights (Hart Publishing, Oxford, 2013) 13; Ortiz, Cummins and Karunanethy, above n 9. 52 Data on the total reserves of states are available at <http://data.worldbank.org/ indicator/FI.RES.TOTL.CD> 53 Radhika Balakrishnan et al, Maximum Available Resources & Human Rights: Analytical Report (Center for Women’s Global Leadership, New Jersey, 2011), 22. 54 Ibid. 55 Ibid.; James Heintz, Central Banks: Do They Have Human Rights Obligations? ESCR-Net <http://www.escr-net.org/node/364736>.