A request is being heard by a Harare court from the Zimbabwe government that could further restrict opposition leader Morgan Tsvangirai and two other people on trial for treason.
The advocate for the three defendants, legendary South African lawyer George Bizos, told the Harare High Court that the state's effort to bar his clients from making political statements was an attempt to gag them.
Mr. Bizos, who defended Nelson Mandela nearly 50 years ago, and was one of South Africa's leading anti-apartheid lawyers told the court that "verbal retorts in the heat of polemic discourse of a political nature is neither treasonable nor incitement to violence."
Mr. Bizos said that in South Africa in 1972, when the country was under apartheid, judges there threw out an attempt by the state to restrict a student leader by altering his bail conditions for reasons similar to those now advanced by the Zimbabwe government.
The state says it submitted the application because it wanted to prevent Morgan Tsvangirai, the leader of the Movement for Democratic Change, and his two co-defendants from making any inflammatory statements or any statements that could incite public disorder.
The state pointed to previous strikes organized by the opposition, which the prosecutor said had caused damage to property and injuries to people.
Mr. Bizos said the state's claims were not backed up by any evidence and would have to be tested. He also said it was inappropriate for the judge presiding over the treason trial to be hearing this application, and could lead to charges of a mistrial.
Mr. Bizos said judges should remain aloof from politics and the divisions caused by disagreements in a society as divided as Zimbabwe's.
Mr. Tsvangirai and colleagues Welshman Ncube and Renson Gasela are accused of planning to assassinate Mr. Mugabe shortly before the disputed presidential elections last year. They have denied the charges.
Meanwhile, most of Harare remained closed Tuesday in the second day of anti-government protests, although some shops began to open after lunch. The opposition reports increasing numbers of its supporters have been arrested or abducted around the country.