From wikipedia:
"In many countries, engineering tasks such as the design of bridges, electric power plants, industrial equipment, machine design and chemical plants, must be approved by a licensed professional engineer. Most commonly titled professional engineer"
"In the United States, engineering is a regulated profession whose practice and practitioners are licensed and governed by law. Licensure is generally attainable through combination of education, pre-examination (Fundamentals of Engineering exam), examination (professional engineering exam),[19] and engineering experience (typically in the area of 5+ years). Each state tests and licenses professional engineers."