There is no law that adult workers in Maryland have a right to meal or rest breaks.
Workers under 18 have a right to a 30-minute break after 5 hours of work.
There is a new law for retail workers that requires breaks.
If you are represented by a union, you may have more rights under your union contract. Read your contract and talk to a shop steward or representative.
Under federal law, workers must be paid for any breaks less than 20 minutes.
Shift break law: http://www.dllr.state.md.us/labor/wages/essretailfaqs.shtml
What is the law: Maryland Annotated Code, Labor and Employment § 3-210 (minor workers)
Who enforces the law: Maryland Department of Labor, Licensing and Regulation, Division of Labor and Industry