I posted this on /r/asklaw but this sub is much more popular and I'm impatient. I remember doing a report on the Salem Witch Trials. I think I read somewhere that in the aftermath it was declared that you could not punish a suspect based on witnessess' alone (regarding those girls claiming they were possessed) Is this true? I tried searching through google and found nothing.
"in october increase mather circulated a tract cases of conscience concerning evil spirits personating men detailing why spectral evidence was unreliable...'better 10 suspected witches should escape...[finish blackstone's famous quote]...not that he said the courts were using spectral evidence'" (Monroe Hellfire nation page 92)
this 1692
don't know any more than is in that book but the work referenced here might be what you are looking for as it coincides with the governor turning against the trials publicly and using pardon power on those who disagreed.
*pseudo stylized citation: don't use it at home kids