What started out three years ago as a delicate legal minuet between Congress and a federal judge over access to House committee documents has suddenly erupted here into an unprecedented constitutional brawl with huffy exchanges, a civil contempt citation and $500-a-day fines filling the judicial air.

In the fast-moving fight, Edward S. Northrop, the feisty 72-year-old senior judge of the U.S. District Court in Baltimore, held Clerk of the House of Representatives Benjamin J. Guthrie in contempt of court June 24 for refusing to surrender subpoenaed documents in a $25 million lawsuit--the first time a high congressional official has ever been held in contempt.

The judge at first delayed a $500-a-day fine on Guthrie, then last weekend ordered it to start running Monday after ruling that objections to the subpoena filed by Guthrie's lawyers were inadequate.

Stunned by Northrop's unprecedented actions, the lawyers filed a notice of appeal today with the U.S. 4th Circuit Court of Appeals in Richmond.

In the interval, Guthrie has refused to pay the daily $500 contempt fine. As of today he owed $1,500 but, under instructions from his lawyers, had made no deposits with the clerk of federal court here as ordered by Judge Northrop.

Northrop, who is vacationing in New Hampshire but has been in almost daily telephone contact with his office here, is not likely to lift the contempt fine, court sources said, but the appeals court in Richmond may do so next week while the matter is being heard there.

The tangled legal case stems from a lawsuit filed in 1979 in federal court here by health insurance agent George H. Benford of Glen Burnie against employes of the House Select Committee on Aging and ABC-TV. Benford contends that committee employes in league with ABC surreptitiously filmed him attempting to sell cancer policies to two committee workers posing as elderly insurance buyers.

Benford contends that the film, parts of which were aired on an ABC news program, invaded his privacy, violated eavesdropping laws and ruined his career. The film was aired in late 1978 when the House committee was investigating allegations that cancer insurance companies were pressuring elderly persons to buy policies they did not need.

In preparation for his lawsuit, Benford sought a wide range of investigative documents from the House committee, but committee lawyers refused to furnish them, contending they amounted to "legislative" files used to formulate laws and were thus shielded from disclosure outside Congress by the Constitution's "speech or debate" clause.

Attorneys for Benford countered that certain documents, such as memos or letters establishing committee arrangements with ABC for the surreptitious filming, fall outside the "legislative" protection and should be given to them. The lawyers took the issue to Judge Northrop, who ordered the subpoena enforced.

Meanwhile, the House by a 386-22 vote passed a resolution ordering Guthrie not to surrender the documents, saying Northrop's order was "an unconstitutional invasion" of the House prerogative to say which of its documents can be disclosed.

In May, Northrop ruled that he had the authority to determine which documents are "legislative" and which are not by private inspection of the documents in his chambers and to enforce a subpoena for them against the clerk of the House.

Then on June 24, after the clerk failed to honor the subpoena, Northrop issued an order saying it was his "distasteful task" to hold Guthrie in contempt of court.

Northrop's action marked the first time that the "Clerk of the House has ever been held in contempt of court in 194 years of legislative history," says Stanley Brand, general counsel to the Clerk of the House. Federal court sources here agreed.