Russia's law banning dissemination of so-called gay propaganda to minors violates the right to freedom of expression, the European Court of Human Rights has ruled.
In the first major court battle for gay activists who have contested the law, 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 (ECHR).
The applicants were awarded some 50,000 euros (£44,000) in total.
Over the course of several years, Nikolai Alexeyev, Nikolai Bayev and Alexei Kiselyov have staged pickets to promote gay rights and unsuccessfully applied for permission to hold gay pride parades in Russia.
"By adopting such laws the authorities reinforce stigma and prejudice and encourage homophobia, which is incompatible with the notions of equality, pluralism and tolerance inherent in a democratic society," the seven-judge panel said in the ruling.
They added that "Russian authorities overstepped the margin of appreciation" of Article 10 of the European Convention on Human Rights that guarantees freedom of expression.
Following legislation in several regions, Russia in 2013 adopted a federal law prohibiting dissemination to minors of "propaganda" legitimising homosexuality.
The law has been condemned as an outright ban on any public discussions of homosexuality while authorities were defending it, citing the interests of children.
The court on Tuesday rejected the Russian government's claim "that regulating public debate on LGBT issues may be justified on the grounds of the protection of morals".
Mr Alexeyev described the ruling as "an enormous court victory for LGBT people in Russia".
"We have managed to legally prove that by adopting those laws, Russian authorities breached their international commitments under the European Convention," he said.
Homosexuality was decriminalised in Russia in 1993, but anti-gay sentiment remains strong.
Mr Alexeyev and other activists have petitioned authorities in Russian cities for permission to stage a gay pride parade, but have been denied.
He along with two other activists has been repeatedly detained and fined for "disseminating gay propaganda".
Mr Alexeyev said Tuesday's ruling will give his advocacy group legal grounds to get the anti-gay law scrapped.
Although the court's rulings are binding, Russia in 2015 passed a law saying that its constitution superseded ECHR rulings.
In the most recent case, Russia's Constitutional Court said in January that the ECHR ruling ordering payment of nearly 1.9 billion euros (£1.6 billion) in compensation to shareholders of the defunct Yukos oil company cannot be enforced.