房玄齢
In 629, Emperor Taizong made Wei the head of the Palace Library, but gave him the additional designation "Canyu Chaozheng" (), making him a "de facto" chancellor. Later that year, when the assistant censor Quan Wanji () accused the chancellors Fang Xuanling and Wang Gui of improper selection of officials, Emperor Taizong initially ordered Hou Junji to investigate. Wei, however, pointed out that both Fang and Wang were trusted officials who should be given free rein and not have the details of their acts be picked on. Emperor Taizong agreed and cancelled the investigations.