Charlot Salwai is facing charges of corruption, bribery and perjury.
It was Deputy Prime Minister, Ishmael Kalsakau, whose complaint led to the trial, who was the first prosecution witness.
Kalsakau told the court a declaration made by Salwai about the appointment of parliamentary secretaries was incorrect.
He claimed a statement made by Salwai, saying his Council of Ministers had approved the roles and appointments of parliamentary secretaries, was wrong.
Last year the Appeal Court ruled the government couldn't create the parliamentary secretary positions.