Gilad Erdan took the stand to discuss Case 4000, in which Benjamin Netanyahu is alleged to have sought regulatory changes that would benefit Bezeq owner Shaul Elovitch.
Erdan will testify on allegations Netanyahu pledged to change regulations to further the interests of Bezeq owner Shaul Elovitch in return for positive news coverage.
Case 1000, a corruption trial in which Netanyahu is charged with fraud and breach of trust, resumed on Monday.
Much of the private legal sector was up in arms on Monday over the reform as many of the largest Israeli law firms - issuing a joint letter against the reform.
Barak added that he was “dumbfounded” that Netanyahu suddenly abandoned talks on a plea deal.
The Movement for Quality Government NGO petitioned the High Court, calling to limit Netanyahu's Prime Ministerial powers.