While there is no specific definition of "best execution" under the U.S. securities laws, market-makers, broker-dealers and investment advisors have a duty to ensure that customers receive best execution on their orders by taking into account all the facts and circumstances surrounding a customer order. Factors a broker-dealer may consider include, among other things, the price of an order, the size of an order, and the trading characteristics of the security involved. The term "best execution" (with different technical implementation details) also has been introduced across the European securities markets through the

MiFID comprises two levels of European legislation. ‘Level 1’, the Directive itself, was adopted in April 2004. In several places, however, it makes provision for its requirements to be supplemented by ‘technical implementing measures’, so-called ‘Level 2’ legislation. Formal Commission recommendations for the Level 2 measures were published on February 6th 2006. The European Securities Committee agreed the text in June 2006, and the measures were formally adopted by the European Commission and published in the Official Journal on September 2nd, 2006.