The Montgomery County Planning Board has hired a prominent Bethesda real estate attorney to investigate possible wrongdoing in the 1999 approval of a Sandy Spring housing development that resulted in an access road used by a predominantly elderly African-American community being dropped from state tax maps.

The board announced Thursday that Douglas M. Bregman will serve as an independent counsel in what has become known as the “Farm Road” case. The road’s disappearance from maps effectively landlocks the community, and leaves property owners with land that has little market value.

According to court cases and recent news accounts, the road was dropped during the approval of Dellabrooke, a subdivision of about 40 high-end single-family homes.

“The community and our stakeholders expect us to clear the air, and our Board needs to understand the facts once and for all,” Planning Board Chair Françoise M. Carrier said in a statement. “We really wanted someone objective with unquestioned integrity, and who is intimately familiar with the complexities of real estate.

Bregman has ranged beyond real estate in his practice. In the late 1990s he represented the National Smokers Alliance, which was fighting Montgomery’s proposed ban on smoking in bars and restaurants. In 2006, he successfully represented a group of immigrant children and pregnant women to have their Medicaid benefits reinstated after they were improperly dropped from Maryland rolls.

Bregman also served as treasurer for County Council member Steven Silverman’s 2006 campaign for county executive.

The inquiry is expected to take several weeks, Carrier said.