I suspect any semi-competent defense lawyer could establish reasonable doubt with respect to intent: “My client approached the mannequin. He saw that it was clearly a mannequin, and not a person. Assuming that it was there as some kind of prank, he decided to prank the pranksters, and took a hammer he happened to have on him, and pretended to ‘kill’ the obviously fake ‘person’. He had the hammer for perfectly normal reasons, and knew perfectly well that the mannequin was fake. Prosecutors — prove beyond a shadow of a doubt that he thought this was a man, not a mannequin. Good luck, prosecutors. You will need it.”
Prosecutors — prove beyond a shadow of a doubt that he thought this was a man, not a mannequin. Good luck, prosecutors. You will need it.”
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I believe the term you are looking for is ‘beyond reasonable doubt’.
Jurors often use common sense. Slam dunk.