T This study examines pretrial decision no. 113/pid.pra/2024/pn jkt.sel, filed by tom lembong, concerning the legality of the notice of commencement of investigation (surat pemberitahuan dimulainya penyidikan/spdp). the discussion focuses on the implementation of the investigation process, which must comply with the principles of due process of law and the principle of legality as stipulated in the indonesian code of criminal procedure (kuhap) and its implementing regulations. this research employs a normative juridical method using both a statutory approach and a case approach. the research data were obtained through an examination of court decisions and relevant legislation and were analyzed qualitatively to assess the legal reasoning adopted by the judges. the findings indicate that the decision provides a progressive interpretation of the function and legal validity of the spdp as an instrument for protecting the rights of suspects, particularly in ensuring legal certainty and transparency in the investigation process. furthermore, the decision reaffirms the role of pretrial proceedings as an essential mechanism for judicial oversight of investigators\\\' actions to ensure their compliance with the law and the principles of justice.