As the U.S. and Russian governments trade accusations over espionage activities and human rights abuses, Baker & McKenzie of counsel Thomas Firestone, a former Justice Department official and liaison to the U.S. embassy in Moscow, has been expelled from the country.

Firestone’s expulsion is the latest episode in a simmering feud between the two countries that began in earnest last December with the passage by Congress of a law designed to penalize Russian human rights abusers. Named for Sergei Magnitsky—a Russian lawyer who died in a Moscow jail under mysterious circumstances after allegedly trying to expose government fraud—the legislation prompted the Kremlin to retaliate with a similar law aimed at Americans.