English to Spanish Law/Patents Law: Taxation & Customs Tratados

Que alternativas hay a disciplinas?
Most governments still view taxation as a central element of sovereignty and so are reluctant to accept extensive or heightened international disciplines on their taxing powers. Thus, whilst accepting supranational control/discipline over state conduct in many other areas, state parties to most modern investment treaties and instruments have either carved out taxation all together from the treaty or restricted the applicability of some of the treaty disciplines to certain types of taxes.