The court found in favour of three gay activists who claimed the law violated the rights to freedom of expression and prohibition of discrimination under the European Convention on Human Rights.
Over the course of several years, the three men have staged pickets to promote gay rights and unsuccessfully applied for permission to hold gay pride parades in Russia.
Following legislation in several regions, Russia in 2013 adopted a federal law prohibiting dissemination to minors of "propaganda" legitimising homosexuality.