While one often hears lawyers and others say "90% of cases settle," this is not consistent with empirical data by University of Hawaii Law Professor John Barkai and Elizabeth Kent of the Hawaii State Judiciary Center for Alternative Dispute Resolution. Their article says "the commonly reported 90 percent settlement rate for all cases is a myth. The settlement rate for 'all' civil cases is about 50 percent (although almost 90 percent of tort cases settle). Trials are rare; jury trials are very rare."
How does settlement negotiation happen in practice? "The most common type of negotiations is telephone negotiations, not face-to-face negotiation, which is the primary method of teaching negotiation in law schools. Telephone negotiations were the event with the greatest impact on settlement. Over 40 percent of cases used some form of ADR process."