A Dutch activist linked to radical antiwhaling group Sea Shepherd Conservation Society was acquitted Wednesday of assaulting a Japanese worker in the whaling town of Taiji, Wakayama Prefecture, in December.

In his ruling on Erwin Vermeulen, 42, Judge Satoshi Shibayama said the Wakayama District Court could not rule out the possibility his accuser was lying and that "there remains doubt over the credibility of the testimony, which is the only evidence" in the case.

Vermeulen was arrested Dec. 16 for allegedly shoving a unnamed man in the chest using his left hand as he tried to force his way onto a seaside road where public access was banned because dolphins were being moved. Vermeulen denied acting violently toward the man, who was blocking his way.

During the trial, Vermeulen's counsel argued that the plaintiff's testimony was not credible and said it would have been physically impossible for the Dutch activist to shove him because both his hands were occupied at the time.

Taiji has become a hotbed for animal rights disputes because of its annual dolphin slaughter, a controversial tradition that entered the global spotlight after being featured in "The Cove," a U.S. film that won the Oscar for best documentary in 2009.