Texte d'origine - Portugais - O advogado é indispensável à administração da...

My first instict was to translate "The lawyer is indispensable to the administration of justice" because of that "à". Then, thankfully before I posted it, I started doubting myself yet again, once more, for one more time (usual state of mind). Is it really "to" or is this a case of "for"?