Bhushan also accused the police of working at the behest of the Narendra Modi government.
According to him, Yadav and some 100-150 people were sitting peacefully on Monday night at Jantar Mantar in the heart of the capital when the police suddenly asked them to end their protest.
"Yogendra Yadav told them (police) that the protest was peaceful. But they did not listen and dismantled the stage and detained the protesters.
"This shows the dictatorial tendency of Delhi Police. It also shows that they are (taking orders from) top political bosses," he added.
The eminent lawyer, who himself was with the Aam Aadmi Party until he and Yadav quit after a showdown with Chief Minister Arvind Kejriwal, said the police didn't explan why they were being arrested.
"I was not even allowed to enter (the police station). It is our constitutional and fundamental right to meet a person who has been detained. They will have to tell us what crime he has been arrested for."
Bhushan said the police were lying for claiming that the protesters were going to march towards the Prime Minister Narendra Modi's residence.
"They have told some media people that the protesters were going to march towards Race Course. This is a lie and baseless."
Yadav and fellow activists were demanding adequate compensation for farmers affected by the proposed land bill as well as those hit by crop loss.