本文試圖從權力鬥爭角度考察永王璘事件的性質，繼而從唐代法律角度探討李白的罪和刑以及遇赦的時間。 永王璘謀反事件，其實是「馬嵬之變」後，玄宗與肅宗父子鬥爭所衍生的政治事件。李白因擔任永王璘從事，成為謀反案的從犯，理當大辟，幸得郭子儀等好友營救，肅宗特予開恩，免死「長流」夜郎。所謂長流，並非法定的三流或加役流，屬於皇帝寬宥嚴重犯罪的一種代刑。一旦被處長流，除非皇帝恩詔特別聲明放免，否則遇赦不赦，永遠不得返鄉。李白判處長流確定後，約於乾元元年（758）春動身上道，同年十月左右抵達流所夜郎，嗣後一直住了三年左右。直到上元二年（761）九月，肅宗大赦天下，赦書特別提到「自乾元元年以前開元以來，應反逆連累，赦慮節度限所未該及者，并宜釋放。」李白因而蒙恩放免。

The purpose of this article is to examine Li Bai’s (李白)banishment to Ye Lang(夜郎) from legal point of view. We attempted to assess it from Li’s crime, his punishment received and finally an amnesty from the Emperor. Rebellion plotted by Prince Yong(永王璘) was the result of the power struggle between the Emperor –Xuan Zong(玄宗) & his son – Su Zong(肅宗) after the｀coup d’ etat of Ma-wei post station’(馬嵬之變). Li worked for Prince Yong, hence, he was assumed as one of the members of the rebel force, and bound to receive capital punishment. Fortunately, Li was rescued by his friends and remitted by Su Zong but specially exiled forever (chang liu 長流) to Ye Lang. Chang liu was not an ordinary banishment .This was a replacement to capital punishment and unless specifically announced by Emperor, otherwise he could not be released even though under a general pardon as well as never allowed to return to the native place. Li started the banishment in the spring of the first year of Qian Yuen (乾元758), and reached Ye Lang in winter that year. He stayed there for 3 years. Till September of 2nd year of Shang Yuen (上元761), Su Zong granted an amnesty, it specified that criminals were implicated in rebellion crimes between Kai Yuen(開元) and first year of Qian Yuen, and was not included in the previous amnesties, could be released. Under this condition, Li Bai was set free.