I would say its more firmly rooted in the tradition than that. The New Testament and the Christian Revelation doesn't have any laws to put forward for the "purpose of determining legislation".
I find it hard to believe the Catholic Church has never strayed beyond the bounds of sacred laws into the realm of the running empires, states and nations. The seperation of Church and State came about through the reformation, did it not? A brief analysis of history will no doubt highlight excellent leadership within the Catholic Church but other times when all manner of boundaries have been crossed. It must be interesting being Catholic and defending nearly two thousand years of history. The twin Prophets of the Baha'i Faith were born just over two hundred years ago so its a little easier.
I'm very positive about the Catholic Church as it has promoted genuine interfaith dialogue and has shifted considerably from the Catholic Church of old. I tend to have few arguments with Catholics as they tend to be more able to amicably agree to disagree, unlike their Protestant brothers. It hasn't always been that way of course.