Canon 830. §1 Every local Ordinary retains the right to appoint persons whom he considers competent to give a judgement about books. The Episcopal Conference, however, may draw up a list of censors who are outstanding for their knowledge, right doctrine and prudence, to be available to diocesan curias; it may even establish a commission of censors whom the local Ordinary can consult.

§2 In carrying out this task, a censor must put aside all preference of persons and look only to the teaching of the Church concerning faith and morals, as declared by its magisterium.

§3 The censor must give an opinion in writing. If it is favourable, the Ordinary may, in his prudent judgement, give his permission for the work to be published, adding his own name and the date and place of the permission. If he does not give this permission, the Ordinary must inform the author of the reasons for the refusal.
[NB see Authentic Interpretation of canon 830 §3, 20.VI.1987]

§1. Integro manente iure uniuscuiusque loci Ordinarii committendi personis sibi probatis iudicium de libris, ab Episcoporum conferentia confici potest elenchus censorum, scientia, recta doctrina et prudentia praestantium, qui curiis dioecesanis praesto sint, aut constitui etiam potest commissio censorum, quam loci Ordinarii consulere possint.

§2. Censor, in suo obeundo officio, omni personarum acceptione seposita, prae oculis tantummodo habeat Ecclesiae de fide et moribus doctrinam, uti a magisterio ecclesiastico proponitur.

§3. Censor sententiam suam scripto dare debet; quae si faverit, Ordinarius pro suo prudenti iudicio licentiam concedat ut editio fiat, expresso suo nomine necnon tempore ac loco concessae licentiae; quod si eam non concedat, rationes denegationis cum operis scriptore Ordinarius communicet.