‘案卷’ (àn juàn) literally combines 案 (àn), meaning ‘case’ or ‘legal matter’, and 卷 (juàn), meaning ‘scroll’ or ‘volume’. Historically, official records were kept on rolled scrolls, so the term evolved to mean a complete set of documents related to a specific legal, administrative, or investigative matter — essentially a formal case file or dossier. It carries a bureaucratic, institutional tone and is used primarily in judicial, governmental, archival, or law enforcement contexts.

The word implies thorough documentation: evidence, statements, rulings, and procedural notes all bundled under one case number or name. Unlike casual terms like 文件 (wénjiàn, ‘document’) or 资料 (zīliào, ‘materials’), 案卷 connotes authority, formality, and legal weight. It’s often found in phrases like 调阅案卷 (diàoyuè àn juàn, ‘to review case files’) or 归档案卷 (guīdàng àn juàn, ‘to archive case files’). While occasionally used metaphorically, its core usage remains tied to official record-keeping systems.