A usually informal arbitration of an existing or impending dispute agreed to by the parties. If the parties choose not to use an arbitration organisation like the International Chamber of Commerce, London Court of International Arbitration, Chartered Institute of Arbitration, Singapore International Arbitration Centre (SIAC), American Arbitration Association, etc. they will likely save on costs, but the procedures may be vague, the seat of the arbitration uncertain and the enforcement difficult. Ultimately the parties to an ad hoc arbitration may want to adapt a set of arbitration rules from some source, for example the UNCITRAL model rules or those of an arbitration organisation to provide structure and parameters to the proceedings.