Q: Must a Maryland employer pay the salary of employee who lives in DC and is required to serve on a jury at DC Supr Ct?

A: In regards to your question about whether this all applies to DC as it does to an MD proceeding, the simple answer is "no." The code section referenced above only applies to actions in an MD court, and the reach of the MD law only covers hearings that the MD Court can control or enforce. Because DC is outside of Maryland's jurisdiction, it cannot control the behavior of individuals attending, or not attending jury in those jurisdictions. There is no "jury consideration" reciprocity between jurisdictions. However, as if the individual is exempt, MD does not recognize a legal payroll deduction for jury time, so payment would have to be made (subject to being offset by anything paid to the employee by the Court). Hourly employees are not required to be paid in either jurisdiction. If the employer terminates the employee, they will run afoul of the US Federal Labor Laws. This would potentially give rise to a federal case of employment discrimination. The Dept. of Labor specifically forbids termination due to jury duty, and reclassifies exempt employees who are "docked" jury time as as non-exampted (this has the potential of costing the employer a considerable amount in unpaid overtime and hourly wages). A succinct summary is here: https://www.shrm.org/resourcesandtools/tools-and-samples/hr-qa/pages/cms_014270.aspx. See also: https://www.law.cornell.edu/uscode/text/28/1875 which reads in part:

(28 USC 1875) "(a) No employer shall discharge, threaten to discharge, intimidate, or coerce any permanent employee by reason of such employee’s jury service, or the attendance or scheduled attendance in connection with such service, in any court of the United States."