Threats and promises. Negotiations conducted under conditions of duress or threat are doomed to failure. There can be no common ground, no meeting of the minds, no real agreements when one of the parties is placed in a totally no-win situation. Nor can negotiations be conducted when promises are made that one of the parties intends to ignore once the settlement is reached. Good faith is the way to go.
Precedents are useful guides in arbitration and in a court of law.
They are not operational in negotiations. No two negotiating situations are identical, so what appears to have been workable in a past situation in all probability will not fit the current situation. Giving to get something by both parties is far more likely to result in a workable agreement. When one of the parties to a negotiating session arrives with ulterior motives or hidden agenda, any agreements that are reached during the meeting are likely to be short-lived. Negotiators must pursue agreements without dissembling.