WASHINGTON LAWYERS, everyone knows, are among the most able in the nation, ready to leap at the Drop of a comma to protect their clients' interests. So imagine their chagrin when they found the D.C. Court of Appeals, which regulates the practice of law in Washington, had slipped one by them.

The court automatically approved a change in the code that governs the conduct of lawyers in a way that could disqualify entire law firms from a case if of one member of the firm was disqualified for things like becoming an alcoholic or getting sick.

Even more embarrassing to Washington lawyers, the rule the court passed came up from the American Bar Association's Code of Professional Responsibility.

D.C. Bar President-elect John H. Pickering of the firm of Wilmer, Cutler & Pickering said both the ABA and the court passed the new rule "without thinking it through."

One Court of Appeals judge, who asked that his name not be used, chucked at the Bar's discomfort. He said court rules call for the automatic adoption for Washington of amendments to the ABA's ethics code unless someone objects. The D.C. Bar now has objected, and formally petitioned the court to return to the old rule, which would disqualify entire firms only if one member was disqualified because of a conflict of interst.

The Bar's Board of Governors, after four long, emotionally charged special meetings, is ready to pass on to the Court of Appeals its recommendations for new rules to jam the revolving door. Predictably, neither those on the board who want strict rules nor those who felt the Ethics Committee's proposals were too strong, are happy.

Pickering said he plans to have a statement of his own opposing the board's revisions, commenting that "I think this bar should be in a leadership position, but I think this bar should be realistic, too."

Replied former Federal Power Commission Chairman Lee C. White, now in private practice and a member of the board calling for stricter curbs: "If you're going to do it, a lot of us are going to do it too."

Before buttoning up the proposal at last Tuesday's meeting, the board eliminated a "grandfather clause" put in by the ethics committee to ease the cry of federal lawyers who said they never would have joined the government if they knew their opportunities to move into private practice would be curtailed. That clause would have exempted lawyers now in government from the new rules.

The other change reversed an earlier board decision for a lifetime ban on a lawyer challenging a rule if he played a major part in getting it adopted while working for Uncle Sam. The new proposal would call for a five-year ban.

The American Bar Association's policy-making House of Delegates will be asked next month to endorse the constitutional amendment to give full voting rights to the District of Columbia. The issue will come up at the ABA's mid-winter meeting in Atlanta, and D.C. Del. Walter E. Fauntroy has been given special permission to address the delegates.

The issue was brought to the ABA's House of Delegates by its Section of Individual Rights and Responsibilities and its Special Committee on Election Reform.

Although the ABA's endorsement carries no force of law, it can be symbolically important in winning passage in the 35 state legislatures that still have to ratify the constitutional amendment passed last summer by Congress.

Meanwhile, Harry Himmelman of Beveridge, Fairbanks & Diamond is organizing a group of volunteer District of Columbia lawyers to help organize support for the amendment from legal groups across the country.

There's a turf battle going on over where the D.C. Bar should locate a law library if it starts one. A vast majority of lawyers who answered a poll in the District Lawyer favored establishing a lobrary and said it should be downtown, where most of them work.

But Chief Judge Theodore Newman Jr. of the D.C. Court of Appeals has told the D.C. Bar that a new library should be near the courthouse complex -- accessible to lawyers who practice there. He said the judges have set aside 10,000 square feet of floor space across from the new D.C. Courthouse for a law library.

"There are no meaningful library facilities down here for the use of the people who practice in the courthouse," said Newman, whose view carries clout since his court controls the purse strings of the D.C. Bar by setting its dues.

Meanwhile, George Washington University law professor and librarian Hugh Y. Bernard complained that Washington lawyers keep trying to use the already overcrowded law school libraries. He said the D.C. Bar is the only one in major cities that does not have "a large, comprehensive, well-housed and adequately staffed and funded bar library." (By all accounts, the libraries run by the Bar Association of the District of Columbia and the Federal Bar Association are too small.)

"In short," wrote Bernard in a letter to the District Lawyer, "never in the legal life of a major city have so many lawyers and such rich law firms done so little to provide themselves with an adequate, cooperative bar library."

Edward J. Skeens of Suitland complained in a letter in the ABA Journal that a Maryland judge refused to let him appear in court because he was not wearing a tie. He said the judge complimented him on his "neat... summer outfit" and said he looked "chic." The outfit, incidentally, was "an expensive white summer leisure suit with an open-necked blue sport shirt," Skeens wrote.

"After 26 years as an active trial practice lawyer without incident. I was flabbergasted," the Suitland attorney said, wondering if there were dress codes in other jurisdictions.

Three old Capitol Hill collegues have gotten together to form a new law firm dealing with -- guess what? -- federal agency and congressional practice. The firm is Randall, Bangert and Thelen and the partners are Donald A. Randall, who left the Hill in 1973 to go into private practice; Charles E. Bangert, who has just quit as staff floor manage of the Senate for Majority Leader Robert Byrd (D-W. Va.), and Dennis C. Thelen, who until 1977 also worked for Byrd as the counsel coordinating bills proposed by Senate committees.

Randall and Bangert worked together in the Federal Trade Commission in the 1960s and on the Senate Judiciary Committee's subcommittee on antitrust and monopoly under the late Sen. Philop Hart. Thelen also worked for the Judiciary Committee, on the subcommittee on criminal law and procedure.

Working with the three partners is Harry Shupe, who has just left the Federal Trade Commission.