When the walls of MAL's red mud holding reservoir burst on 4 October 2010, 10 people were killed and 150 injured as 1.1 million cubic metres of red mud escaped into the area surrounding the plant.
Last year, MAL was ordered to pay US$615 million to regional environmental authorities but was allowed to continue production.
The 2010 red mud spill was billed as Hungary's worst chemical disaster.
In addition to negligence, Bakonyi and his 14 co-defendants have been charged with waste management violations and environmental damage.
The hearings will be held in Veszprem, near the disaster site, but nobody knows when the verdict will be announced. Witness hearings are to be held at the court in Veszprem, near the site of the disaster, until late October. It was unclear when a verdict was expected.