A Sea Shepherd dolphin activist, held for two months in jail in the town of Taiji over an alleged minor assault, has been cleared of the charge in a very rare finding by a Japanese court.

Erwin Vermeulen, a volunteer with the Cove Guardians group of Sea Shepherd protesting against the Taiji dolphin hunt, was arrested after he was said to have shoved an employee of the Dolphin Resort Hotel.

At the time, Mr Vermeulen was trying to take photographs of Risso's dolphins as they were being transferred between holding pens at the resort, Sea Shepherd said.

He was detained until last week, and a "not guilty" decision in his case was handed down today, Sea Shepherd leader, Paul Watson, said.

"The Japanese judge said there was no evidence to support the claim.

"Erwin says he is very happy and that the judge showed great courage in going against public opinion and ruling fairly."

Japanese courts have a 99.7 per cent conviction rate, according to a 2005 paper by US academics Mark Ramseyer and Eric Rasmusen.

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