Nihil obstat

Nihil obstat (Latin for "nothing hinders" or "nothing stands in the way") is a phrase traditionally used by Catholic Church authorities to formally declare that there is no objection to the publication of a book, or to some other proposed action.

Publishing
The phrase nihil obstat is used by a Catholic cleric known as a Censor Librorum (Latin for "censor of books") to indicate that a book contains nothing contrary to Catholic doctrines, faith, or morals. Canon law requires this approval for the publication of books by faithful Catholics if they "touch upon matters of faith and morals", and requires that pastors enforce this rule. The Censor Librorum is delegated by a bishop to review the text in question over approximately two months. If an author is a member of a religious institute (such as a monastery) and the book concerns religion or morals, then canon law further requires the imprimi potest ("it can be printed") of the major superior before publication. Finally, the bishop of the author's diocese or of the place of publication gives the final approval, the imprimatur ("let it be printed").

Marriage
A nihil obstat also refers to the document declaring that someone is free to marry due to lack of form in the previous marriage. It can also refer to a document of dispensation from certain impediments to marriage in the Catholic Church.