* EU governments set to impose sanctions on Russia over Ukraine
* Iran experience shows sanctions must be legally watertight
* Sanctions could be difficult to challenge in court
By Justyna Pawlak
BRUSSELS, March 13 (Reuters) - The European Union is taking extra care in drawing up sanctions against Russia over Crimea to avoid legal loopholes that could allow targeted officials to challenge them in court, as happened with measures against Iran's nuclear programme.
If, as expected, EU foreign ministers approve a list on Monday of people, firms or institutions they blame for harming the territorial integrity of Ukraine, the bloc may still have to defend the measures in court, legal experts and diplomats say.
But those hoping to sue to get their names off the list may have a tough case to make.
EU officials have already started drawing up the list after agreeing the framework this week for measures to freeze assets and impose travel bans. The final decision will only come after Sunday's referendum held by pro-Moscow authorities in Crimea on bringing the Ukrainian Black Sea province under Moscow's rule.
Washington has announced similar plans for travel bans and asset freezes and also has yet to unveil its target list.
In the past, Brussels has lost cases in EU court over sanctions imposed on Iranian firms when targeted companies successfully asserted that Brussels had not proven their involvement in Iran's nuclear programme. Those cases became a headache for Brussels although they did not substantially weaken the overall sanctions programme.
EU diplomats say the bloc's lawyers have pressed them to make sure that the names they include on the Russia list will stand up in court. Proof must be provided that those on the list were responsible for "actions which undermine or threaten the territorial integrity, sovereignty and independence of Ukraine", as spelled out in the framework approved this week.
"The legal services said sanctions must be legally watertight and there must be a clear link between the framework and the subject," one diplomat said.
Another said: "The crux is to match the names with the criteria and to have the evidence."
One lawyer with a private firm in London who has represented people targeted by EU sanctions in the past said the push for sanctions on Russians had generated many inquiries about the potential impact and legal standing of the measures.
The lawyer said the wording of the sanctions framework over Russia may make it easier for Brussels to defend legal challenges from Russians than it proved in the case of Iran.
Domestic politics in Russia would make it hard for officials to assert that they opposed President Vladimir Putin's Ukraine policy, said the lawyer, speaking on condition of anonymity because of prior involvement in sanctions cases.
"My hunch is it could be difficult to win such cases," the lawyer said, "It is legitimate to assume that anyone in government is part of government policy unless they distance themselves. And they may not want to do that." (Reporting by Justyna Pawlak; Additional reporting by Luke Baker and Megan Davies; Editing by Peter Graff)