Cross-border mergers and acquisitions (M&A) have become more difficult over the past five years, a survey of heads of legal at 100 multinationals has revealed. Respondents to the poll, commissioned by City firm Norton Rose, blamed ever-increasing levels of regulation in developed jurisdictions and dealing with 'unknowns' in emerging jurisdictions for the increasing complexity of the M&A process. Key headaches include the Sarbanes-Oxley legislation in the US and antitrust legislation in Europe. The respondents claimed China is the toughest environment in which to conclude M&A transactions because of its underdeveloped legal framework and complex bureaucracy. The US, France and Russia were identified as the next most difficult. Some 41% of the companies interviewed also admitted that they did not have a comprehensive global compliance system in place.