This article examines the correlation between arbitration and constitutional law by comparing decisions from nine jurisdictions where there has been a challenge to the constitutionality of the arbitration act or an act imposing the use of arbitration. Such challenges are made in different ways. Sometimes they are direct, that is, a direct challenge to the core of the act; and sometimes they are incidental – a challenge to a constitutional guarantee connected to the arbitral process. The aim of the study is to assess if such challenges are a real violation of a constitutional right, or if this is just a tactic made by parties wishing to delay or avoid arbitration that they have previously agreed to. The study compares the rationale behind the challenges and assess the common grounds in which they were raised. Through the comparison, the study concludes that for compulsory arbitration there is a valid argument in the challenges. Nevertheless, for voluntary arbitration, although the challenges are not completely trivial, they do not represent a risk to the practice of arbitration; in effect, they appear to be more like a technique used to procrastinate the enforcement of an arbitral award.