Zimbabwe's opposition leader, Morgan Tsvangirai, and his two co-defendants have asked the high court in Harare to dismiss the treason charges against them. The men say the prosecution has failed to meet one of the basic legal requirements for conviction.
The head of the defense legal team, attorney George Bizos, told the court the government has not provided two credible witnesses, as required by law.
Mr. Bizos says the government's two key witnesses are not credible, in part because their company received a large consulting contract from the Zimbabwe government.
The witnesses are Canadian political consultant Ari Ben-Menashe and his assistant Tara Thomas. They testified that Mr. Tsvangirai approached their company to arrange the assassination of President Robert Mugabe. Mr. Ben-Menashe secretly made a video recording of a December 2001 meeting, during which Mr. Tsvangirai is alleged to have made the request.
Mr. Tsvangirai and his co-defendants deny the charge, and the audio on the videotape is difficult to understand. The defense lawyer described the meeting as at attempt at entrapment, in exchange for money. He also said Mr. Ben-Menashe's and Ms. Thomas's evidence contradicted each other.
The trial, which began in early February, adjourned two weeks ago after all the state witnesses had taken the stand. The prosecution will respond to the defense motion later this week, and the judge will then consider the matter.
If convicted Mr. Tsvangirai and his co-defendants face the death penalty. Even if these charges are dismissed, Mr. Tsvangirai faces another treason trial resulting from his call for a widely observed five-day general strike in June.