From Wikipedia:
In 2001, Baba Santa Singh, the Jathedar of Budha Dal, along with 20 chiefs of Nihang sects, refused to accept the ban on consumption of bhang by the apex Sikh clergy.[13] Baba Santa Singh was excommunicated for helping the Indian congress government rebuild the Akal Takht in 1984[14][15] he was replaced with Baba Balbir Singh, who shunned the consumption of bhang.[16]
Source: http://en.wikipedia.org/wiki/Nihang