Basil was educated at Bumayong Lutheran Secondary School and was a businessman prior to entering politics, where he was managing director of seafood and aquaculture company BSJ Fishing and Trading.

[17][18] In July 2010, Prime Minister Michael Somare told Basil during a parliamentary no-confidence vote "if you were outside I would kill you", which received wide media attention.

[4][24] In May 2012, a reported crowd of 10,000 came to witness his renomination for the 2012 election, at which he stated that he was defending his seat to finish incomplete projects in his ten months as minister.

[25] He was re-elected, standing for the Papua New Guinea Party, in July, receiving an absolute majority of the vote in a crowded field of candidates.

[26] O'Neill dumped the PNGP from his governing coalition after the election, having fallen out with leader Namah, costing Basil his ministry.

[28][29] Basil was again named Deputy Opposition Leader in August 2012, while also serving as Shadow Minister for National Planning, District Development and Health and HIV/AIDS.

[35] Basil was heavily critical of the deal which allowed for the expansion of the Manus detention centre, and was involved in an opposition legal challenge claiming that it was unconstitutional.

[39][40][41] In June 2014, Prime Minister O'Neill asked police to investigate Basil and sacked anti-corruption head Sam Koim, claiming that they had colluded to oppose him.

[53] On 3 May 2016, Basil became Leader of the Opposition after the National Court upheld a challenge to Polye's 2012 election victory, set aside the result and ordered a belated recount of votes in his seat.