An exclusive dealing arrangement is a commercial agreement under which a supplier agrees to supply goods or services only to a particular customer, or a customer agrees to purchase some or all of its requirements only from a particular supplier, excluding competitors. In UK and Irish legal practice this is a descriptive competition law and commercial contracts term rather than a defined statutory concept, though it is addressed in competition legislation and guidance (including the UK Competition Act 1998, the EU/UK Vertical Agreements rules and the Irish Competition Act 2002). Key legal issues concern whether the arrangement forecloses market access for rivals, its duration, the parties’ market power and any loyalty or exclusivity rebates. Exclusive dealing may infringe the Chapter I / Article 101‑type prohibitions on anti‑competitive agreements or, where a dominant firm is involved, the Chapter II / Article 102‑type rules on abuse of dominance. Similar principles apply in England and Wales, Scotland, Northern Ireland and Ireland, with enforcement by the CMA or the Competition and Consumer Protection Commission. In practice, lawyers assess exclusive dealing arrangements for block exemption coverage, market‑share thresholds, objective justifications and appropriate drafting to mitigate competition law risk.