mandatory

This term carries a heavy sense of obligation and authority, often associated with legal statutes, official policies, or institutional requirements. It implies that there is no choice or option for the individual; failure to comply typically results in a penalty or a formal sanction. While similar to "compulsory," this word is frequently used in professional, governmental, or academic settings to describe specific requirements like training, sentencing, or vaccinations. It suggests a structured system of rules rather than a general social or moral obligation.