From 1994 to 2008, Sem composed and played bass guitar in the band "Caesar", performing many shows both in the Netherlands as well as abroad. Caesar released a total of 5 albums and had two hits. The second album won them the prestigious Dutch "Silver Harp" award. This recording was released under the title ‘No rest for the lonely’ by China records in the UK in 1998. The third album was recorded by Steve Albini, famous for his work with Page & Plant and Nirvana.
Since 2005 Sem has been teaching intellectual property law at the InHolland University of Applied Sciences to students International Music Management. Sem also teaches regularly at the Nyenrode New Business School of Amsterdam. Further Sem lectured intellectual property rights and international business law at universities in Norway and Finland.
In 2008, Sem founded Van Heemstra Bakker together with Hugo van Heemstra. Sem joined Rohe Advocaten as a partner in June 2010.
Rohe Advocaten is an Amsterdam based law firm that provides comprehensive legal services with a focus on cultural and media industry clients. Rohe Advocaten is committed to providing innovative, cost-effective and practical legal services regarding national and international issues. Rohe Advocaten differentiate themselves by having a deeper understanding of their clients' industry environments and business needs.
Sem is member of the board at public broadcaster HUMAN and regularly advises pop musicians, dj’s, record labels and other music related companies.