wwwreuterscomyukos– Jason Bush is a Reuters columnist. The views expressed are his own —

Former Yukos shareholders are set to sue Russia for up to $100 billion in damages after an international court ruled in their favour. Successful claims against a sovereign state are rare. But the case is embarrassing for Russia. If successful it could even lead to the confiscation of Russian assets.

The biggest problem for the former shareholders of the bankrupt oil group was proving that international courts had jurisdiction in the matter. But they have found an ingenious way to make their case, suing Russia under the Energy Charter Treaty, which protects investors in Russia’s energy sector. Russia signed this treaty, but never ratified it, creating ambiguity over whether it is actually binding.

The answer, according to yesterday’s ruling by the Permanent Court of Arbitration in The Hague, is that it is. That’s extremely worrying for Russia. The legal justifications for its actions against Yukos have long met with widespread scepticism abroad.

The core shareholders’ stake was worth an estimated $25 billion at the time Yukos was dismantled, but the litigants are asking for a multiple of that amount to reflect Yukos’s estimated capitalisation today and interest.