So just exactly when is a negotiation over? 

I’m pretty sure that by now you know that this is a loaded question – a negotiation is never over.  Even after we’ve been able to use our negotiation styles and  negotiating techniques to reach a deal with the other side, we still  need to make sure that they will keep their word and do what they  promised that they would do. However, things can get just a little bit  trickier if after the deal has been signed the other side comes back to  you. The reason that they’ve come back is because they want a renegotiation of the deal. 

What’s a negotiator to do now?