NOW THE NAME of Rep. Charles C. Diggs Jr. (D-Mich.) has been added to the list of congressmen who have faced criminal charges. Mr. Diggs - perhaps best known in this town as chairman of the House District Committee - has been indicted on charges that he defrauded Congress of $101,000 by padding his payroll with nonexistent employees and taking kickbacks from three staff members, apparently to pay off personal debts. Under the technical language of the indictment, which apparently was personally approved by Attorney General Griffin B. Bell, Mr. Diggs is charged with 14 counts of mail fraud and 21 counts of making false statements.

It should go without saying that an indictment by a federal grand jury is not a conviction. That judgment must await the outcome of a trial; in the meantime, Mr. Diggs must be presumed innocent.That said, it does no violence to a presumption of Mr. Diggs's innocence to note that being a congressman is a full-time job and that the preparation of a defense in a criminal case as serious as this one is a heavy burden. We would not suggest that Mr. Diggs resign his seat; he has no cause to, and the constituency that elected him is entitled to his representation in Congress for the balance of his term. The voters can pass their judgment on his conduct at the next election. But we do suggest that the congressman might well consider voluntarily relinquishing some of his congressional committee responsibilities until the case is concluded. We have particularly in mind his two most important and time-consuming committee chairmanships - of the District Committee and the International Affairs subcommittee on Africa. We emphasize the word voluntarily, since there is neither a legal nor a House requirement that he do so - which is fair. The question is whether Mr. Diggs will have sufficient time between the business of defending himself, running for reelection, traveling in Africa (where he is right now) and overseeing the various legislative and research efforts that his massive District Committee staff has taken upon itself to handle.

The decision is up to Mr. Diggs, but by temporarily removing himself as chairman of the committee and the subcommittee, he could assure residents of this community that the necessary congressional oversight of the District, and House business having to do with urgent and critical African issues, will not be given short shrift while he is otherwise occupied.