Maryland law can be found here:
http://www.michie.com/maryland/lpext....htm&cp=mdcode (Search for "impeding")
(or BaltimoreSpokes.org | links | Law | LexisNexis )
What's being thrown at us is in the Drivers' Manual
http://www.mva.maryland.gov/resources/dl-002b.pdf pg 68 paper (pg 36 electronically)