This paper analyses the process known as a ‘third-party expert determination’ (ED), where, by virtue of an ED clause in the contract, the parties agree to refer an issue, difference or dispute to an expert, whose decision is final and binding on them. In particular, it examines the validity of the oft-repeated proposition that the grounds for challenging ED are very limited, and argues that this oversimplifies the true state of the law, and that ideas of freedom of contract and party autonomy are insufficiently implemented in the law on ED. This paper proposes solutions that promote finality, which is vital to the effectiveness and reliability of the ED process, and that restrict room for judicial interference. Further, the paper demonstrates the increasing complexity of the law on ED and advocates approaches that are conducive to greater legal certainty.