An arbitration clause contained in the original contract retains full effect with respect to disputes arising from subsequent agreements amending or supplementing the same contract, where such agreements do not constitute a new and autonomous contractual relationship, but merely redefine specific aspects of the existing relationship, such as consideration, performance terms or methods of performance, without affecting provisions not expressly modified.
The characterisation of a subsequent agreement as a mere amendment or supplement to the original contract, rather than as a new autonomous contractual source, must be determined from the nomen iuris attributed by the parties, from the actual subject matter of the provisions and from the severability clause preserving contractual provisions not expressly derogated from, with the consequence that the arbitration agreement originally entered into maintains its scope of application also with respect to claims based on the amending agreement.