Claim construction is a major phase of a patent litigation where the meaning and scope of the claims themselves - the invention - is determined by the court. The outcome of this definition phase is crucial to the respective infringement and invalidity positions of the parties. The Thesaurus of Claim Construction directs practitioners to cases-and in contrast to searches on more general electronic databases, only those cases-in which claim terms have previously been construed, and further to the sources of the evidence used by previous courts to construe the terms in dispute.