Putin studied Law at the Leningrad State University named after Andrei Zhdanov (now Saint Petersburg State University) in 1970 and graduated in 1975. His thesis was on "The Most Favored Nation Trading Principle in International Law". While there, he was required to join the Communist Party of the Soviet Union and remained a member until it ceased to exist (it was outlawed in August 1991). Putin met Anatoly Sobchak, an assistant professor who taught business law, and later became the co-author of the Russian constitution and of the corruption schemes persecuted in France. Putin would be influential in Sobchak's career in Saint-Petersburg. Sobchak would be influential in Putin's career in Moscow.