Till the late 1980s, he pursued principally an academic career, although he acted as a consultant to governments and international organizations.
B. Quigley, Jr.); Northeast Arctic Passage (Leiden, Martinus Nijhoff, 1978); an edition of P. P. Shafirov, Discourse on the Causes of War between Russia and Sweden (Dobbs Ferry, Oceana Publications, 1973); Comparative Approaches to International Law (1978); Documents on Socialist International Organizations (1978); Russian Law: Historical and Political Perspectives (Leiden, A. W. Sijthoff, 1977); The Soviet Legal System (in co-authorship with John N. Hazard and Peter B. Maggs; 3d ed.
In 1982 Butler founded the Centre for the Study of Socialist Legal Systems, University College London, which in 1993 was renamed The Vinogradoff Institute and in 2005 was removed to Dickinson School of Law.
For many years he was a member of the Council of the School of Slavonic and East European Studies, University of London, including one term as Vice-Chairman.
He is the author, co-author, editor, or translator of more than 3,500 books, loose-leaf services, articles, and reviews on Soviet, Russian, Ukrainian, Belarusian, Tajik, Uzbek, Kazakh, Baltic, and other CIS legal systems.
Commencing in 2004, he became the founding editor of Russian Law: Theory and Practice, issued by the Russian Academy of Legal Sciences (2004–2009) and Consulting and Book Review Editor, elevated from 2008 to co-editor (with Professor Michael Palmer) of The Journal of Comparative Law (London, Wildy, Simmonds & Hill, 2005-).
Commencing with Mikhail Gorbachev's perestroika and onwards, Butler became more deeply involved in consulting activities, providing expertise for the legal reforms in the USSR and its successor states.
In 1989 he was appointed Special Counsel and Chairman of a Working Group attached to the Commission for Economic Reform of the USSR Council of Ministers.
In this capacity, he evaluated key draft perestroika legislation and was co-author of the Draft USSR Law on Pledge which, in May 1992, was the basis for legislation enacted by the Russian Parliament and then for similar laws adopted in Belarus, Kazakhstan, Kyrgyzstan, Turkmenistan, Ukraine, and Uzbekistan.
The same Working Group prepared the Edict of the President of the Russian Federation on Trust Ownership, adopted on 24 December 1993 and still in force.
Pursuing the same subject, in 2009 the United Nations Office on Drugs and Crime in Moscow published his study on the legal aspects of substitution therapy in Russia.
In particular, in February 2005 he appeared as a legal expert before the US Bankruptcy Court for the Southern District of Texas in Houston within the litigation between Russian oil giant Yukos, on the one hand, and Deutsche Bank and Gazpromneft, on the other.
In 1993 he founded the Faculty of Law of the unique Russian-British postgraduate university – the Moscow Higher School of Social and Economic Sciences attached to the Academy of National Economy of the Russian Federation.
[4] He has acted as Of Counsel to Cole Corette & Abrutyn (1988–92) and Clifford Chance (1992–94) and as Partner and head of the CIS London Group and the Almaty and Tashkent offices of White & Case (1994–96).