Tosefta sur Les Nombres 15:30

There is a stringency in erroneous rulings that there is not in capital cases, and [a stringency] in capital cases that there is not in erroneous rulings: [As to the former, a judge is not liable for] an erroneous ruling until all [the judges] issue the ruling as one (see Hor. 1:4), but in capital cases we follow the majority. [As to the latter, a judge is not liable for] an erroneous ruling unless the ruling is issued by the beit din presiding in the Chamber of Hewn Stone (i.e., the Sanhedrin), but in capital cases, [a judgment may be] issued in any place. An individual who issues (i.e., executes) an erroneous ruling by his own order, behold he is liable, as it is said (Num. 15:30), "But the person who acts high-handedly ... [shall be cut off from among his people]."