OOO FLAVUS AND OTHERS v. RUSSIA JUDGMENT applicants’ websites blocked in their entirety or identified specific web pages which might have featured illegal content. Nor had they carried out an assessment of the proportionality of the blocking measures. 50. The third-party intervener, the European Information Society Institute, submitted that both ex ante and ex post remedies needed to be made available to the affected parties. Ex ante remedies should include prior notification to the owners of targeted websites. Ex post remedies should ensure that, once a blocking order had been implemented, there were efficient mechanisms for restricting its scope or challenging it on account of new circumstances. 51. The Court notes at the outset that at the material time a cassation appeal was not considered an effective domestic remedy (see Berkovich and Others v. Russia, nos. 5871/07 and 9 others, § 69, 27 March 2018, with further references). 52. The Court further notes that the complaint under Article 13 arises from the same facts as those it has examined when dealing with the complaint under Article 10 above. However, there is a difference in the nature of the interests protected by Article 13 of the Convention and those protected under Article 10: the former affords a procedural safeguard, namely the “right to an effective remedy”, whereas the procedural requirement inherent in the latter is ancillary to the wider purpose of ensuring respect for the substantive right to freedom of expression (see Iatridis v. Greece [GC], no. 31107/96, § 65, ECHR 1999-II). Having regard to the difference in purpose of the safeguards afforded by the two Articles, the Court considers it appropriate in the instant case to examine the same set of facts under both provisions. 53. The Court finds that the applicants had an arguable claim of a violation of their right to freedom of expression. Accordingly, Article 13 required that they should have had a domestic remedy which was “effective” in practice as well as in law, in the sense of preventing the alleged violation or its continuation, or of providing adequate redress for any violation that had already occurred. 54. Although the applicants were able to bring proceedings seeking a review of the blocking measures and their effect on the operation of their online media, the Russian courts did not consider the substance of their grievances. They did not address the authorities’ failure to comply with the legal requirement to identify the problematic webpages or examine the necessity and proportionality of the blocking measures or their excessive scope. Accordingly, the Court finds that the remedy which the national law provided for was not effective in the circumstances of the applicants’ case (see Elvira Dmitriyeva v. Russia, nos. 60921/17 and 7202/18, § 64, 30 April 2019). 55. There has therefore been a violation of Article 13 of the Convention, taken in conjunction with Article 10. 17