Salwai is facing 10 counts of bribery and corruption under the Leadership Code, and a separate charge of perjury.
The former minister of agriculture and a current Luganville MP, Matai Seremaiha, the former minister of health, Jerome Ludvaune and former MP Tom Korr are also facing bribery and corruption charges.
The case was filed following complaints by the former leader of the opposition and now deputy prime minister, Ishmael Kalsakau.