A party-appointed expert (expert des parties) is a specialist mandated by one party to a legal dispute or proceeding to produce a technical or financial analysis supporting that party's position. They differ from a court-appointed expert (who is independent) in that they act as an advocate for the appointing party's interests, while remaining bound by professional standards of rigour. In financial valuation disputes, party-appointed experts produce competing valuation reports, and the court or arbitrator adjudicates between the two positions — sometimes appointing a neutral expert to resolve the disagreement.

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Example: in a post-acquisition dispute over a CHF 1.8 million earn-out calculation, the seller appoints Hectelion as party expert to challenge the buyer's calculation. Our report demonstrates a CHF 420,000 error in the buyer's exclusion of qualifying revenue — supporting a claim for the full earn-out amount. The report is submitted as evidence in the arbitration proceeding.

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Hectelion serves as party-appointed expert in financial valuation disputes and earn-out litigation, producing technically rigorous and legally defensible expert reports.