Leadership of the DOT is provided by the secretary of transportation, who is the principal adviser to the president in all matters relating to federal transportation programs. The Office of the Secretary oversees the formulation of national transportation policy and promotes intermodal transportation. Other responsibilities range from negotiation and implementation of international transportation agreements, assuring the fitness of US airlines, enforcing airline consumer protection regulations, issuance of regulations to prevent alcohol and illegal drug misuse in transportation systems, and preparing transportation legislation.