The treason trial of Zimbabwean opposition leader Morgan Tsvangirai and two other officials from his party is now in its sixth day at the High Court in Harare.
The entire morning session was taken up by arguments over the admissibility of documents presented by the defense.
The documents are said to cast a shadow over the character of the state's key witness, Ari Ben Menashe. He claims that, before last year's presidential elections, the three opposition Movement for Democratic Change officials offered him a large amount of money to assassinate President Robert Mugabe, and make it look like an accident.
Defense lawyer George Bizos said the documents, primarily newspaper articles, show that Mr. Menashe has a history of making claims that were later proved to be false relating to elections in two other countries, the United States and Australia.
Mr. Bizos said, since the documents were in the public domain, it was in order to use them as evidence.
The prosecution argues that the articles should not be used as evidence, since they are mostly newspaper articles that express the opinions of the writers.
The trial judge is expected to rule on the matter when the trial resumes later on Friday.
Mr. Tsvangirai and his co-defendants, Movement for Democratic Change Secretary-General Welshman Ncube and member of parliament Renson Gasela, deny the charges. They face the death penalty if found guilty of treason.