It seems to be de rigueur among arbitration practitioners and scholars to advocate for the most extensive scope of the principle of Kompetenz-Kompetenz, including a French-style negative effect. The present article examines this principle with special focus on its negative effect, first generally, then with respect to several jurisdictions, followed by a focus on Spain, including Spanish doctrine and case-law. The article also scrutinizes the arguments made in support of the different approaches regarding the scope that should be given to the principle of Kompetenz-Kompetenz, both generally and particularly in the Spanish context. The analysis suggests that the arguments in favour of the negative effect are less compelling and universally applicable than might be expected, and that in fact, under the current state of Spanish law, such a negative effect à la française is neither prescribed by legislation, nor endorsed by the courts, nor actually desirable.