62 from Article 13(2) of the Convention to be in compliance with it. Given their relevance to the case at hand, the IACHR will now clarify the scope of each of the three preconditions mentioned above, as they relate to the principles of judicial independence and impartiality. 205. Under Article 13(2) of the American Convention, any limitation or restriction of the right to freedom of expression must be expressly established by law. The jurisprudence constante of the InterAmerican Court has been that it must be a law in both the formal and material sense and establish in clear and precise terms the grounds for subsequent imposition of liability to which the exercise of freedom of expression may be subject.285 Therefore, it has held that vague or ambiguous provisions that grant discretionary powers to the authorities are incompatible with the American Convention, because they can support potential arbitrary acts that are tantamount to prior censorship or that establish disproportionate liabilities for the expression of protected speech.286 206. The precision and rigor of the language of provisions that provide for restrictions on freedom of expression is a function of the severity of the restriction.287 Thus, limitations imposed through criminal law are subject to the strictest test of legality, and must meet the requirements established in Article 9 of the Convention,288 under which “[n]o one shall be convicted of any act or omission that did not constitute a criminal offense, under the applicable law, at the time it was committed.” The same is true of limitations imposed through punitive administrative proceedings, especially when such proceedings can lead to such serious sanctions as dismissal. The Inter-American Court has written that Article 9 of the Convention applies to these proceedings, since they “constitute an expression of the State’s punitive power” that implies impairment, denial or alteration of individuals’ rights as a consequence of unlawful conduct.289 207. To determine the legitimacy of a measure that severely restricts the right of expression in the case of judges and magistrates, it is not sufficient that such restriction be clearly and precisely spelled out in the law. Under Article 13(2) of the Convention, a determination must be made as to whether the restriction is lawful and justified under the American Convention. As previously observed, Article 13(2) of the Convention provides that the exercise of the right to freedom of expression is subject only to subsequent imposition of liability, which shall be established by law to the extent necessary to 285 I/A Court H.R., Compulsory Membership in an Association Prescribed by Law for the Practice of Journalism (Arts. 13 and 29 American Convention on Human Rights). Advisory Opinion OC-5/85 of November 13, 1985. Series A No. 5, paragraphs 39-40; I/A Court H.R., Case of Palamara Iribarne v. Chile. Judgment of November 22, 2005. Series C No. 135, paragraph 79; I/A Court H.R., Case of Herrera Ulloa v. Costa Rica. Judgment of July 2, 2004. Series C No. 107, paragraph 120; I/A Court H.R., Case of Tristán Donoso v. Panama. Preliminary Objection, Merits, Reparations and Costs. Judgment of January 27, 2009. Series C No. 193, paragraph 117; IACHR. Annual Report 1994. Chapter V: Report on the Compatibility of Desacato Laws with the American Convention on Human Rights. Title IV. OEA/Ser. L/V/II.88. doc. 9 rev. February 17, 1995; IACHR. Report No. 11/96. Case No. 11,230. Francisco Martorell. Chile. May 3, 1996, paragraph 55; IACHR. Arguments to the Inter-American Court in the Case of Ricardo Canese v. Paraguay. Transcribed in: I/A Court H.R., Case of Ricardo Canese v. Paraguay. Judgment of August 31, 2004. Series C No. 111, Paragraph 72 (a). 286 See IACHR, Report of the Office of the Special Rapporteur for Freedom of Expression 2009, OEA/Ser.L/V/II.Doc. 51, December 30, 2009, Chapter III, paragraph 71. 287 Cf. I/A Court H.R. Case of Kimel v. Argentina. Judgment of May 2, 2008. Series C No. 177, Paragraph 59 et seq 288 Cf. I/A Court H.R. Case of Baena Ricardo et al. v. Panama. Merits, Reparations and Costs. Judgment of February 2, 2001. Series C No. 72, paragraphs 105-108. 289 Cf. I/A Court H.R. Case of Baena Ricardo et al. v. Panama. Merits, Reparations and Costs. Judgment of February 2, 2001. Series C No. 72, paragraphs 106 and 108.