Manikavasagam was elected to Parliament in the 2008 election, winning the seat of Kapar, previously held by the Barisan Nasional coalition. Before his election, Manikavasagam was a prominent leader in the Hindu Rights Action Force (HINDRAF).
In December 2008, Manikavasagam announced he would leave Keadilan, citing disappointment with the party's leadership in Selangor. He eventually resigned from a leadership position within Keadilan, but not from the party itself.
In June 2009, an arrest warrant was issued for Manikavasagam after he allegedly refused to respond to a subpoena to testify to an inquest into the death of an actress. Manikavasagam applied to have the warrant set aside, and eventually testified at the inquest. Less than two weeks later, Manikavasagam was arrested over an unrelated public demonstration.