2019年，臺灣修正《道路交通管理處罰條例》，增訂規定，對於搭乘酒後駕車之成年乘客科以行政罰鍰。立法者刻意選擇不就乘客一方設定任何主觀構成要件，因而在行政責任之成立要件及其舉證責任配置上，引發實務與理論上之爭議。本文檢視相關行政法院裁判，整理司法實務就主觀過失是否為行政罰成立要件，以及行政機關與當事人間舉證責任分配所呈現之歧異見解。本文進一步將該爭議置於《行政罰法》制定及其學說爭論之脈絡中加以分析，指出司法實務之見解分歧，實反映立法者未能妥善調和法治原則與執法效率考量，而刻意以規範不明確性留待司法填補之結構性結果。本文認為，行政法院對該規定之不同詮釋固非理想，然其制度根源主要在於立法設計本身，而非司法適用之恣意。本文並以此案例補充對臺灣立法與司法互動關係之理解。

In 2019, Taiwan introduced an offence that punishes passengers of a vehicle driven by a drunk driver. The offence was introduced under a deliberate legislative decision to omit any mens rea requirement vis-à-vis the passenger. I comprehensively survey how the Taiwanese courts have applied this new offence, and document the disparate judicial approach towards the burden of proof of mens rea. I further situate this offence with the earlier reform of the administrative penalty regime, and argue that the otherwise undesirable disparate judicial interpretations are the inevitable consequence of unresolved legislative tension between the lofty rule of law ideals and practicalities of enforcement expediency. More broadly, this case study adds to the literature on legislature-judiciary dynamic that has thus far focused on Taiwan’s polarized political landscape. I highlight how overwhelming political consensus can produce legislations that are as equally fraught for the courts to handle.