Evidence is decisive to prove one’s case and indeed the most important aspect of construction litigation. In complex Nuclear Power Plant (NPP) construction disputes, where delay claims frequently generate conflict between the parties, the evidence brought by the parties before national courts, arbitral tribunals or adjudicators supporting project delays is frequently fact intensive and extremely vast. A study commissioned by the International Court of Arbitration (ICC) Commission on International Arbitration produced by the Construction Arbitration Section of the Commission’s Forum on Arbitration and New Fields suggested the creation of a working document briefly recording the essential elements of each party’s case, established from exchanges between them. In establishing technical entitlement both contractor and owners have been utilizing over the years certain delay analysis techniques or forensic schedule analysis methods in order to demonstrate the effect of the different factors upon delays.