In 2001 the New South Wales (NSW) Bureau of Crime Statistics and Research developed a simulation model of the NSW criminal justice system to provide a means of assessing the impact of legislative, policy, or resource changes on the system. A detailed description of the model was presented in the 2001 report entitled "Simulating the New South Wales Criminal Justice System: A Stock and Flow Approach" (Lind, Chilvers, and Weatherburn). The model consists of five stocks, four court stocks and one prison stock. Persons awaiting determination of court cases are placed in one of the court stocks. When the case is finalized, the person may move to the prison stock or exit the system. As monthly blocks of persons move through the model, entering through the police process at the local court level, they are diverted to another stock or out of the system in proportions determined by parameter values calculated from previous years' data. The current report documents progress in addressing some of the deficiencies identified in the model in the concluding discussion of the 2001 report. These deficiencies were the lack of data necessary for parameter estimation, particularly data on case registration in the courts; the inability of the model to simulate a court's response to a backlog of cases; and the lack of predictive accuracy for some measures. This report begins with a description of changes in parameter estimates that have resulted from the availability of more recent data and new data sources. This is followed by a section on other improvements in the model, including the method for setting bounds on court finalization and determination of initial stock values. The combined effect of these improvements is then demonstrated by comparing the predictive performance of the new version of the model with that of the original model. Other sections of this report discuss some additional developments, notably the introduction of seasonal changes in input used to predict future population levels and the migration from spreadsheet to modeling software, as well as planned future developments. 9 figures, 8 notes, and appended diagram of the criminal justice system model