Settlement of a dispute by a person or persons chosen to hear both sides and come to a decision. In 2001 the Permanent Court of Arbitration (PCA) adopted the Optional Rules for Arbitration of Disputes Relating to the Environment and/ or Natural Resources ("Environmental Rules"). The Environmental Rules seek to address the principal lacunae in environmental dispute resolution. The Optional Rules for Conciliation of Disputes Relating to the Environment and/ or Natural Resources were adopted in 2002. These Rules provide the most comprehensive set of environmentally tailored dispute resolution procedural rules presently available. The PCA also provides guidance on drafting environmentally related dispute settlement clauses.