subject to the foregoing

Hi, Heather.
There are several possibilities, but if you want to use the same wording as the official translation, I recommend you to use this one.
You are doing an easy “homework”.
All the best,
Manuel
==

Artículo 3
(…)
e) Todo Estado tiene derecho a elegir, sin injerencias externas, su sistema político, económico y social, y a organizarse en la forma que más le convenga, y tiene el deber de no intervenir en los asuntos de otro Estado. Con sujeción a lo arriba dispuesto, los Estados Americanos cooperarán ampliamente entre sí y con independencia de la naturaleza de sus sistemas políticos, económicos y sociales.
[Protocolo de Reformas a la Carta de la Organización de los Estados Americanos
”Protocolo De Washington”, Washington, D.C., el 14 de diciembre de 1992; <http://www.oas.org/juridico/spanish/tratados/a-56.html>]


Article 3
(…)
e) Every State has the right to choose, without external interference, its political, economic, and social system and to organize itself in the way best suited to it, and has the duty to abstain from intervening in the affairs of another State. Subject to the foregoing, the American States shall cooperate fully among themselves, independently of the nature of their political, economic, and social systems;
[Protocol of Amendment to the Charter of the Organization of American States “Protocol of Washington”, December 14th, 1992; <http://www1.umn.edu/humanrts/oasinstr/washington1997.html>...]