Platt served in three different branches of the
Prince George's County, Maryland courts from 1978 to 2007: Orphans' Court, District Court, and the Circuit Court. Maryland's district courts are courts of limited
jurisdiction over criminal misdemeanors and limited types of felonies, and civil cases worth less than $30,000. Orphans' courts handle
probate and estate matters. The circuit courts are courts of
general jurisdiction over serious criminal matters, major civil cases, and juvenile, family law, and domestic violence cases. Unlike district courts, cases in the circuit courts may be heard before a judge or a jury. Platt was a judge of the Orphans' Court from 1978 to 1986, serving as its Chief Judge in 1985 and 1986. From 1986 to 1990 he served as a judge in the Prince George's County District Court. From 1986 to 1988, he was cross-designated to the county's circuit court, the 7th Judicial Circuit, and he was the district court's Administrative Judge from 1988 to 1990. Platt began his service as a circuit court judge on the 7th Judicial Circuit on May 7, 1990, and served there until January 15, 2007. He was the Coordinating Judge of the Family Law Division from 1993 to 1997, and Coordinating Judge for Criminal Operations from 2001 to 2003. While serving on the circuit court, Platt was chair of the Strategic Planning and Total Quality Management Council from 1995 to 2001, and chair of the Strategic Planning Committee from 2001 to 2007. Platt also served as chair of the 2005 Auto Crimes Court Feasibility Study Committee for Prince George's County. He is recognized as an architect of the Prince George's circuit court's Drug Court Program. He retired as a full-time judge in January 2007. Platt has been approved for judicial recall service in all of Maryland's circuit courts. As recently as May 2024, Platt was issuing significant rulings in climate change cases brought against major oil companies by the City of
Annapolis in the
Anne Arundel County, Maryland circuit court.
Platt as a business court judge and leader Platt played a central role in creating a statewide
business court in Maryland's circuit courts, known as the Business and Technology Case Management Program (BTCMP), which became operational in 2003. In 2000, he was vice-chair of the legislatively created Business and Technology Division Task Force, which produced a report recommending creation of a business and technology court program in Maryland's circuit courts. In 2001, Maryland's Court of Appeals (now known as
Maryland's Supreme Court) created the BTCMP Implementation Committee, making Platt chair of that committee. That committee produced a report setting out the details, design, and goals for implementing the BTCMP across Maryland's circuit courts. This included a recommendation, among others, that the Conference of Circuit Judges create a standing committee to operate in connection with the development of the BTCMP. Subsequently, Platt was made the first chair of the Conference of Circuit Judges BTCMP's Designated Judges and Implementation Committee, which he led from 2001 to 2007. As a specialized business court judge handling cases himself, Platt was the 7th Circuit's Designated Supervising Judge for BTCMP cases from the program's actual opening in 2003 until his retirement in 2007. In 2012, as part of the United States
Department of Commerce's Commercial Law Development Program, Platt was among three commercial court judges (including
Ben F. Tennille and Dubai's chief commercial court judge), who spoke in Dubai to a group of Iraqi judges in the early stages of creating commercial courts in Iraq, on developing best practices for court procedures and case management systems in their new court. == Work and positions before and after being a judge ==