The Latin expression nihil obstat means literally "there is nothing standing in the way." As a contemporary canonical term nihil obstat is employed in at least two ways: to name the kind of evaluative judgment that an ecclesiastical censor makes about a writing submitted for approval prior to publication, and to describe the form of clearance given by the Holy See to a person who is eligible for certain kinds of teaching positions in ecclesiastical faculties.
In the context of the Church's discipline on the censorship of books (cc. 823–832 in the 1983 Code of Canon Law), the local ordinary (usually the diocesan bishop) appoints a censor to review books which are submitted for the ordinary's permission to publish (imprimatur ). The censor makes a judgment about the book by comparing it to or measuring it by "the teaching of the Church about faith and morals as it is proposed by the ecclesiastical magisterium" (c. 831). The censor grants the nihil obstat if he or she perceives that the writing will not be harmful to the faith or morals of the Christian faithful. It is an essentially negative judgmenṭ "I detect nothing harmful; I have no opposition." In making this decision censors should bear in mind the maxim which Pope John XXIII applied to this process, "In essentials unity, in debatable questions liberty, in all things charity" [Acta Apostolicae Sedis 51 (1959) 867].
In the context of the regulation of ecclesiastical faculties, which are those empowered by the Apostolic See to grant academic degrees having canonical effects in the Church (c. 815–821), the nihil obstat is required for those teachers who are to be given permanent tenure or a promotion to the highest rank of the professoriat [Sapientia christiana (April 15, 1979) n. 27; Act ApS 71 (1979) 483]. The nihil obstat is granted by the Congregation for Catholic Education. No criteria for making the judgment have been published, hence the grounds for giving or withholding the nihil obstat are obscure. The nihil obstat of the Holy See is the declaration that there is nothing to impede a nomination which is proposed.
[j. a. coriden]