I have already asked this question.

There are 'penalty' in LN for those who're trying to cheat. But who is The Referee to decide who is a cheater and who is setting up a counterparty as a cheater?
In other word, who or what prove/certify the last LN transaction from A to B was N and not N+1, which B has just dropped in order to set up A as a cheater and therefore steal coins of A as 'penalty'?