You could say the same thing about almost any law. The difference between an accidental fire and arson is criminal intent. While in theory it's not possible to

You could say the same thing about almost any law. The difference between an accidental fire and arson is criminal intent. While in theory it's not possible to observe someone's inner mental state, in practice their outward actions usually give a pretty good clue, and edge cases where the same actions could be interpreted either way are rare. The same is true in spoofing: while it's theoretically possible that exactly the same strategy might be used by a legitimate trader and by a spoofer, differing only by intent, in practice some strategies are overwhelmingly more likely to be spoofing. The edge cases are tricky, but they don't invalidate the entire concept. In this particular case, the trader in question would have been financially ruined if his spoofed orders had been executed, so it's pretty clear he didn't intend for them to be. Caveat: In my opinion, this isn't a distinction well suited to the criminal justice system. I'd rather that exchanges identify probable spoofers and ban them from trading (after some warnings), with the burden of proof (in arbitration) on the accused to show that the suspicious orders were part of a legitimate strategy.