MGL 152, § 1 (4) states that an employee is "every person in the service of another under any contract of hire, express or implied, oral or written." Exceptions include but are not limited to:
Seamen engaged in interstate/foreign commerce;
Salesmen of real estate or consumer goods who work on a commission, or buy/sell basis, other than in a retail establishment, (with a written contract stating they are not treated as an employee under federal tax law);
Taxi drivers who lease their cabs on a fee basis not related to fares collected (and who are not treated as an employee under federal tax law);
Persons engaged in interstate/foreign commerce who are covered by federal law for compensation for injury or death.