Soesilo in his book Kitab Undang-Undang Hukum Pidana serta Komentar-Komentarnya Lengkap Pasal Demi Pasal is:
“Sexual intercourse committed by a married man or woman with a person who is not their lawful spouse.”
Apart from being prohibited by religious principles, infidelity may also contribute to the breakdown of a marriage. Where infidelity involves adultery, the husband or wife of the person committing the adultery may report the conduct to the police.
Under the former Article 284 of the Indonesian Criminal Code (KUHP), adultery constituted a complaint-based offense (delik aduan), meaning that criminal proceedings could only be initiated upon a complaint by the parties specified under the law. The provision applied to a married person who committed adultery as well as the unmarried person involved with them.
Where the conduct constitutes adultery under the applicable criminal law, the parties involved may be subject to imprisonment of up to nine months, provided that the required legal elements are proven.
Therefore, not every act of infidelity automatically constitutes a criminal offense. The legal consequences depend on the nature of the conduct and whether the applicable legal elements of adultery or another criminal offense are satisfied.
