Supporters of an unsuccessful election candidate in Kiribati claim the winner of the South Tarawa seat Kourabi Nenem was involved in treating.
Mr Nenem became Vice President after the elections at the beginning of this year.
Supporters of Arobati Teewe have brought legal action, claiming Mr Nenem's backers had offered food and kava during the campaigns.
Lawyer for the claimants, Taoing Taoaba, says she has about nine witnesses, while the defendant says he also expects the same number to testify.
Counsel for the defendant and MP Banuera Berina says he is worried three days for this hearing is not enough.
Chief Justice Sir John Muria urged witnesses to attend the court hearing and give their testimony amid reports some witnesses do not want to be seen testifying against the Vice President.