In the predominantly adversarial framework of international criminal law, the investigative phase of international criminal proceedings is largely driven by the prosecution. Although the regulatory structure of each of the international criminal tribunals accords the chambers varying measures of control during the investigative phase, investigative decisions and activities remain largely within the purview and discretion of the prosecution. That discretion, however, is also bounded by rules which explicitly recognise and protect the rights of suspects and other relevant actors during the investigative phase.

At the ICTY, ICTR, and SCSL, the chamber plays only a minor and relatively reactive role in the investigative phase. With no input into the initiation of investigations or regulatory control over the conduct of the investigation, the chamber's role is largely a facilitative one, issuing such orders in aid of the prosecution's work as may be necessary to secure state cooperation. The ICC pre-trial chamber, conversely, plays an authoritative role in certain aspects of the prosecution's investigative activities. Investigations initiated by the ICC Prosecutor proprio motu must be authorised by the pre-trial chamber before they can proceed. Additionally, the ICC Prosecutor's decisions not to initiate an investigation or not to prosecute following an investigation are both subject to confirmation by the pre-trial chamber in certain instances. Apart from this enlarged gatekeeping function, however, the ICC pre-trial chamber's role in the conduct of the investigation is largely similar to the other tribunals – facilitating without controlling.