The Willem C. Vis International Commercial Arbitration Moot or Vis Moot is established in 1994. Since that time it has been held annually in Vienna, Austria attracting more than 300 law schools from all around the world and spurring the creation of more than 20 pre-moots each year before the actual rounds are held in Vienna. It is the largest moot in the world for its field and is considered a grand slam or major moot. A sister moot, known as the Willem C. Vis (East) Moot, is held in Hong Kong just before the rounds in Vienna. It was established in 2003 and attracts around 150 teams every year, making it the second-largest commercial arbitration moot. It uses the same moot problem as the Vis Moot, as do the various pre-moot friendlies.
The problem for the moot is always based on an international sales transaction subjected to the United Nations Convention on Contracts for the International Sale of Goods (CISG) and also involves procedural issues of arbitration such as jurisdiction and powers of an arbitral tribunal. The moot consists of submitting written memoranda for both claimant and respondent before the oral phase of the competition, though the written arguments have no bearing on progress in the oral phase.