A couple of days ago I said I don't want to know your bottom line because I cannot guarantee it will not effect my own neutrality.
Listen, here's the toughest part of being a mediator -- making a conscious effort not to pursue the weakest party for the purpose of settling the litigation.
You tell me your bottom line and you throw temptation in my path, temptation that I'd rather avoid. Keep your counsel on this one with any mediator.
We're neutral. We're not saints.
That's Rule No. One.
What's Rule No. Two?
The second reason for not telling your mediator your bottom line is to avoid letting any number influence you and your own client.
The single best predictor of the outcome of a negotiation is how much money you believe the other side has to settle the case. (skip the statistics in this article on the effect on negotiation outcomes of the first five minutes of a negotiation session and go directly to the Conclusion section on page 13)
Depending upon the size of your case or the passion of your commitment to a particular client, you've already spent a few sleep-interrupted nights trying to figure out just what in the heck the other side is thinking.
The other side has also spent a few daytime hours sending you overt or covert smoke signals for the purpose of influencing your estimate of their ability to settle the case anywhere near a dollar figure you'd be willing to settle it for.
Because of our "blind spot" to biases you may well have already formed an impression of what the other side will pay that influences you without your knowing it. You concretize (get stuck in) that blind spot if you commit to any number before the day of the negotiation.
Though you should know your BATNA (basics here) to avoid accepting a bad deal in the heat of the moment, I'd recommend you have at least two or three reasonable numbers with principled reasons for deploying them. Then you can rock and roll to the music that gets played on the day of the settlement negotiation -- a session that often brings surprises that benefit you, i.e., a negotiating partner more eager to settle than you'd anticipated for instance.
If you bring a single hard and fast bottom line number with you to the day of the negotiation, you may well narrow your window of opportunities based upon the other side's intentional or unintentional signals concerning their willingness to pay something between $X and $Y.
It's not rocket science, but it is an art.