In the anime
series Big O,
this message scrolls across the console
of the Big O Megadeus
mecha when its pilot, Roger Smith
, activates it.
There has been some speculation among fans as to the origin or etymology of the phrase. Some have claimed that it was engraved upon the sword of a legendary or historic knight or crusader. Others believe that it refers to the Biblical admonishment, "Let he who is without sin cast the first stone." Finally, some suggest that it is just a poetic login acknowledgment, left in the Megadeus operating system for forgotten reasons.
This expression has become a rather popular sig quote among anime fans of late -- possibly because of its very mystery. It's certainly more welcome in that capacity than, say, All Your Base.
Update: dragoon has pointed out that in the version of Big O shown in the U.S. by Cartoon Network, this line is redacted to "Cast in the Name of Good, Ye Not Guilty". Presumably this was done because someone thought that giant robots aren't supposed to talk about God, or some such ....