Montgomery County District Court Judge Henry J. Monahan, charged with breaking and entering and with assaulting two police officers three weeks ago in Hagerstown, Md., has been assigned administrative duties until his trial this summer in Washington County District Court.

"He is doing administrative paperwork in chambers dealing solely with civil cases," said Robert F. Sweeney, chief judge of the District Court for Maryland, in a telephone interview yesterday. "He will not sit on the bench in any cases and he will have no involvement of any kind in criminal or motor vehicle cases until his own case is resolved."

Monahan, 52, returned to work in Gaithersburg Monday. His trial on misdemeanor charges is set for July 17. Sweeney said he had not chosen who will preside over Monahan's trial, a decision the chief judge said is difficult because the Maryland judiciary is tightly knit.

Monahan was arrested by Washington County police about 2 a.m. May 3 after partying in Hagerstown with other judges attending an annual meeting of the Maryland judiciary. Answering a call from a couple who said someone was trying to break into their house, police found a man, later identified as Monahan, inside the enclosed front porch. The man, whom police said appeared to have been drinking, attacked two officers with his hands and gave several false names, police said.

Monahan was later released to the custody of Baltimore District Court Judge Robert J. Gerstung, who said Monahan had been drinking and also "appeared to be a very sick and distraught and disoriented person."

Because Monahan had suffered a heart attack in December and has only one kidney, Gerstung took him to Washington County Hospital, where he was advised to see his cardiologist, Gerstung said. Monahan was admitted to Georgetown University Hospital that day and was released May 8, Sweeney said.

Only two other Maryland judges have faced criminal charges, Sweeney said. Baltimore County District Court Judge David N. Bates resigned last year after he was found not guilty of making false declarations to a federal grand jury. In 1981, Baltimore District Court Judge Allen B. Spector resigned after he was convicted of accepting bribes as a Baltimore councilman.