Md. Code Ann., Bus. Reg. § 10-319

Before a retail or wholesale delivery of motor fuel may be made in a container, the vehicle operator shall remove all liquid volume of:

(1) gasoline, if the next delivery will be special fuel; or

(2) special fuel, if the next delivery will be gasoline.

Official source: Maryland General Assembly. Reproduced from public-domain Maryland statutes; confirm against the official source for the current text. Not legal advice.