 In 680, he was given the designation of "Tong Zhongshu Menxia Sanpin" (同中書門下三品), making him a chancellor "de facto".Later that year, when Emperor Gaozong's crown prince Li Xian was accused of treason, Emperor Gaozong had him, Xue Yuanchao, and Gao Zhizhou investigate.Eventually, Li Xián was deposed and replaced by his brother Li Zhe.