The document states that Russia was responsible for Litvinenko's poisoning with radioactive polonium in the UK in 2006.
The court ruled that Russia had not conducted an effective investigation into the case and had not prosecuted Russians Andrey Lugovoi and Dmitry Kovtun, whom British investigators had called the perpetrators.
In addition, the ECHR ordered Russia to pay more than €100,000 of compensation to Litvinenko's wife, Maria Anna Carter aka Marina Anatolyevna Litvinenko.
Earlier, it was reported that the former employee of FSB Alexander Litvinenko died of poisoning by the radioactive substance polonium 210 in November 2006. According to Scotland Yard, polonium was mixed into tea by State Duma deputy Andrey Lugovoy (a former colleague of Litvinenko in FSB) and businessman Dmitry Kovtun, who in the past was a member of the Main Intelligence Directorate.
In January 2016, The Guardian reported that a London court had found Russian President Vladimir Putin "probably" involved in Litvinenko's death.
The suspects and Kremlin officials, in turn, deny involvement. Russia also refuses to extradite its citizens to court.
Alexander Litvinenko served as a lieutenant colonel of Soviet and Russian state security, from 1988 to 1999 he worked in the KGB (FSB). In 2000, he fled to the United Kingdom, where he was granted political asylum. In his book, Blowing Up Russia, Litvinenko accused the security services of involvement in the 1999 apartment bombings and other terrorist attacks aimed at bringing Vladimir Putin to power.