Primary Holding

Immunity under the ADB Headquarters Agreement does not apply to criminal acts like defamation; lower courts must allow both parties to present evidence on whether alleged acts were performed in an official capacity.

Background

Jeffrey Liang, an ADB employee, was charged with defaming a colleague. The MeTC initially dismissed the case based on a DFA protocol letter asserting immunity, but the RTC reversed this decision.

Facts

• 1. Jeffrey Liang (Huefeng), an economist at the Asian Development Bank (ADB), was accused of making defamatory remarks against a Filipino coworker, Joyce Cabal, during a staff meeting in 1994. Liang allegedly claimed Cabal was "incompetent and professionally dishonest." Cabal filed criminal charges for grave oral defamation. The Metropolitan Trial Court (MeTC) initially dismissed the case based on a Department of Foreign Affairs (DFA) letter asserting Liang’s immunity under the ADB Headquarters Agreement. The prosecution contested this, arguing the dismissal ignored due process and bypassed their right to rebut the immunity claim. Liang’s defense maintained the statements were part of official duties, while prosecutors asserted slander fell outside protected functions.

Arguments of the Petitioners

• 1. Claimed immunity under Section 45 of the ADB Agreement.
• 2. Alleged lack of preliminary investigation rendered charges invalid.

Arguments of the Respondents

• 1. Immunity applies only to official acts, not criminal behavior like defamation.
• 2. MeTC violated due process by dismissing the case without hearing the prosecution.

Issues

• 1. Does diplomatic immunity cover defamation charges?
• 2. Was due process violated when the MeTC dismissed the case without prosecutorial input?
• 3. Is a preliminary investigation required for MeTC cases?

Ruling

• 1. Immunity under Section 45(a) of the ADB Agreement is limited to official acts; slander is not an official function.
• 2. Lower courts must allow both parties to submit evidence on whether the act was official.
• 3. Preliminary investigations are unnecessary for MeTC cases.

Doctrines

• 1. Functional immunity: Immunity only applies to acts within official duties (United States v. Guinto).
• 2. Prosecutorial due process: Courts cannot blindly accept DFA immunity claims without hearing the prosecution.
• 3. Statutory preliminary investigation: No right to preliminary investigation unless expressly granted by law.

Precedents Cited

• 1. United States v. Guinto: Immunity applies only to official acts.
• 2. Chavez v. Sandiganbayan: Immunity claims don’t automatically void charges.
• 3. People v. Casiano: Preliminary investigations aren’t required for MeTC cases.

Statutory and Constitutional Provisions

• 1. Section 45(a) of the ADB-Philippines Headquarters Agreement.
• 2. Section 31(1)(c) of the Vienna Convention on Diplomatic Relations.
• 3. Rule 112, Section 1 of the Rules of Criminal Procedure.