The GB will claim that they are not accountable, that their instructions were merely "suggestions" or "recommendations" and that those who chose to follow them were doing so completely voluntarily, based on their understanding of Scripture™.
However, when the choice to set aside those teachings in favour of, say, saving their child's life with a blood transfusion is consequenced with expulsion from the Congregation™ and being shunned by friends and family, how "voluntary" is it to comply? And who is responsible for the individual JW's understanding of Scripture™ in the first place, particularly when to hold a different understanding is equated with Apostasy™?
When a person is under duress, such as when a gun is held to their head, and commits a crime, they are not really committing that crime voluntarily, are they? In that case, who is accountable for the commission of the crime?