While Catholics are bound by the sacraments, God is not. God, if necessary, can work beyond and outside them, because of his transcendence and authority over the very sacraments themselves, and that is exactly the reasoning the Church uses with this question.
I have to admit, I’ve been beside myself for a couple weeks now in anticipation for Pope Francis’ first trip (in his whole life!) to the United States.
With the release of Pope Francis' most recent encyclical, Laudato Si ("Be Praised"), this question is a particularly appropriate one. Generally, an encyclical is simply a letter written by the pope to a group of individuals for teaching purposes and for the well-being of the Church and the world as a whole.