The defence team of the main opposition leader in Kuwait, former MP Mussallam al-Barrak, walked out of court on Monday after the judge refused requests to hear defence witnesses, a lawyer said.
Barrak faces charges of making statements deemed offensive to the ruler of the oil-rich Gulf state at a public rally on October 15. If convicted he could be jailed for up to five years.
"We walked out of the session... after the court refused repeated appeals to hear our defence witnesses," Mohammad Abdulader al-Jassem told AFP.
"We said this is an illegal practice."
Jassem said that the defence team had demanded to hear the testimony of several dignitaries including Prime Minister Sheikh Jaber Mubarak al-Sabah, former opposition MPs Khaled al-Sultan and Jamaan al-Harbash and others.
After the defence team left the courtroom, Barrak asked judge Wael al-Atiqi to postpone the trial until he finds a new lawyer, but the judge refused and set April 15 as the date to issue a verdict, Jassem said.
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The court had been expected to hear the final arguments of the defence team during Monday's hearing.
Jassem said the decision to set a date to announce the ruling without hearing the defence arguments was "illegal", and "any ruling on the case will be null and void."
Barrak, a key leaders of the opposition, was detained for four days in late October and released on bail. He is also facing trial on several other counts including charges of storming parliament and taking part in protests.
Dozens of Barrak supporters staged an unprecedented protest outside the courtroom in late January when the court did not allow them to attend the trial.
Several opposition tweeters and former MPs have been sentenced to jail terms on charges of insulting the emir.
Kuwait's opposition has been staging protests to demand the dissolution of parliament elected last December on the basis of an electoral law that had been amended by the emir.
The opposition claims that the change is illegal and is aimed at electing a rubber stamp parliament.