There were many Catholic restrictions on divorce, abortion, birth control, imprimatur, nihil obstat, etc.
Good Catholics were kept on a taut, short leash. The League of Decency imposed the Index of forbidden books on all literature considered to be riddled with error. Philosophers like Voltaire were outlawed and their books were forbidden, for sure.
The Index of Forbidden Books was our general guideline to acceptable literature when I was growing up in Lowell-town. Dating back to 1559 and the Curia of Pope Paul IV, this official, papal declaration was the “sine qua nun” on scholarship for Catholic adherents.