Complex sentence: Legal regulation of multinational corporations is difficult because they are not under the control of any one jurisdiction; rather, they are subject to multiple legal systems including the country of their corporate headquarters as well as the countries in which they operate.
Split into simpler sentences: Legal regulation of multinational corporations is difficult because they are not under the control of any one jurisdiction. Rather, they are subject to multiple legal systems, including the country of their corporate headquarters as well as the countries in which they operate.