As from 1 January 2010, Tore Wiwen-Nilsson practices as a sole practitioner with focus as independent arbitrator and advisor on primarily nuclear energy law. He was a partner of Mannheimer Swartling Advokatbyrå since its creation through the merger of Mannheimer Zetterlöf Advokatbyrå and Carl Swartling Advokatbyrå in 1990, and before that a partner of Mannheimer Zetterlöf Advokatbyrå since 1974.
Tore Wiwen-Nilsson has a spent most of his professional life as advisor in international transactions of various kinds in many countries of the world, including construction projects, foreign direct investments, industrial alliances, cross border licensing and technology transfers, business acquisitions, project finance, etc. As lead counsel, he advised the Swedish Government in relation to two of the largest infrastructure projects in Sweden, the Öresund Link, a bridge and tunnel between Sweden and Denmark, and the Arlandabanan Project, the privately financed railway connection between the Arlanda Airport and Stockholm City. Tore Wiwen-Nilsson has had various assignments to the United Nations Commission on International Trade Law ("UNCITRAL"), such as a member of the UNCITRAL Group of Legal Experts for Privately-Financed Infrastructure Projects (1996-2002), Swedish delegate at many meetings of UNCITRAL and Chairman of UNCITRAL (2003/2004), and he has been and is presently chairman of Working Group 1 of UNCITRAL.