A lawyer, Kumar fought cases for economically and socially backward people, without taking any fees. He first met Arvind Kejriwal, who was later instrumental in founding the AAP, during the
India Against Corruption movement in 2012. Kumar contested the
2013 Delhi Legislative Assembly elections as an AAP member in the
Sultan Pur Majra Assembly constituency. He secured 30,346 votes, finishing second to the sitting
MLA Jai Kishan of the
Indian National Congress (INC), by a margin of 1,112 votes. The AAP re-nominated Kumar for the constituency in the
2015 Delhi Legislative Assembly elections. He won with 80,269 votes. He defeated Kishan, who finished third, by 64,439 votes. He was described as a "giant killer" by
The Financial Express for defeating the four-times elected Kishan. He was also placed in charge of the social welfare and language ministries. With average age of 42 years, the cabinet was described as the "youngest" in the country, and 34-year-old Kumar was its youngest member. == Sexual assault allegations ==