Can the Prosecutor Amend the Complaint After Further Investigation Conducted Post-Filing?
The Supreme Court of Thailand ruled that a public prosecutor cannot amend a criminal complaint based on findings from a new investigation conducted after the complaint was already filed, if the original filing lacked a proper prior investigation.
Under Section 120 of the Criminal Procedure Code (CPC) and Section 6 of the 2016 Act on Criminal Procedure for Corruption and Misconduct Cases, a prosecutor must conduct a valid investigation before filing a complaint.
If no proper investigation was conducted, the complaint is legally invalid, and cannot be amended later to correct or add new facts.
Section 15, Paragraph 3 of the 2016 Act allows amendments only if the original complaint was legally valid but incomplete—not if it was invalid from the outset.
The Supreme Court rejected the prosecutor’s argument that further investigation after filing counts as satisfying the legal requirement for prior investigation.
As a result, the Court held that the trial court was wrong to permit the amendment, and confirmed that such post-filing investigations cannot cure an originally invalid complaint.
This decision reinforces the necessity of a legally sufficient investigation before filing in corruption and misconduct cases.