How much discretion or leeways of choice should be enjoyed by judges and others whose job it is to apply the law? Negotiating by the Light of the Law reports on a project where the researchers tested claims made about the relative merits of fixed rules and discretionary principles on negotiation in legal disputes. The researchers selected contrasting norms extracted from family law and contract law for testing, undertook an extensive literature review and created simulation experiments for lawyers. The findings provide valuable insight into whether more or less discretion is conducive to settlement, and into the way lawyers negotiate.