[5] In Siwan, Kushwaha became an activist for farmers' and dalits' rights and stepped in to intervene to assure protection of the rights of Dalits when in 2013 upper caste landlords of the region attempted to attack them with the help from a Bhartiya Janata Party MLA.

[2][8] During the 2019 Indian general election, Kushwaha worked for the campaign of Amarnath Yadav in the Siwan constituency.

[12] He is one of the prime accused in Chilmarwa massacre, which took place in Guthni Police station area of his constituency.

Kushwaha was arrested along with another CPI-ML Member of Legislative Assembly, Satyadeo Ram and was made an accused of murder under section 302 of Indian Penal Code.

While he remained under imprisonment in connection with the murder, Ram got bail after latter's victory in 2015 Bihar Assembly elections.

While CPI-ML leaders Satyadeo Ram and Amarjeet Kushwaha intervened to protect the rights of Dalits, the landlords, supported by goons attacked them with the intent to displace the inhabitants.