Multi-party arbitration arises when a dispute involves more than two parties — for example a main contractor, a subcontractor and an employer — or when related disputes span multiple contracts containing separate arbitration clauses.
The main complication is the appointment of the tribunal: if three claimants and one respondent each try to nominate separately, the usual one-nominee-per-side model breaks down. Institutional rules typically address this by requiring multiple parties on one side to jointly nominate, or by providing that the institution appoints the entire tribunal where joint nomination fails.
Consolidation of related disputes into a single arbitration is possible only where the parties have agreed to it, whether in the original clauses or afterward — tribunals cannot consolidate unrelated proceedings on their own initiative without that agreement.