How Do I Open A Closed Adoption?

My mother gave my sister up for adoption in 1972. It was a closed adoption my Catholic Service. My mother died in 1997. We have found one another. We look just a like. Anyway, what all does she need to open those records. Do I have to get our mother's birth certificate, death certificate in order for her to open it? Does a judge have to grant permission? We need some advice or help. Please!!!