If Mr. Hayes is tried or enters into a plea agreement in the U.S., British prosecutors wouldn't be able to try him on similar charges under U.K. double-jeopardy rules, according to criminal-defense lawyers who aren't involved in Mr. Hayes's case.
Not surprisingly, jury-tampering is suspected, and the case was appealed to the Russian Supreme Court. (Double-jeopardy rules don't exist in Russia, and 25% to 50% of criminal cases are reversed on appeal.) The lead prosecutor has spoken of "gross violations" of procedural laws but won't elaborate publicly.