A COMPASSIONATE public can feel only sorrow for the John Fedders family, whose misfortunes are in the news now chiefly on account of the conjunction of Mr. Fedders' high position -- until yesterday he was enforcement chief of the Securities and Exchange Commission -- and his wife's complaints, which he has acknowledged in a divorce trial, that he beat her repeatedly for over 16 years of marriage. It is a cautionary tale that tells much about the ambitions and stresses that can blight the lives of people who on the surface appear to have almost everything going for them.

A particular question, however, arises from the disclosure that the White House, in the person of counsel Fred Fielding, learned months ago of Mrs. Fedders' complaint, and sat on it. After hearing President Reagan denounce "horrible crimes like sexual abuse and family violence," The Wall Street Journal reported, she wrote Mr. Reagan; the letter was not mailed, but a friend sent Mr. Fielding a copy. Just before the November election, the Journal said, a sister of Mrs. Fedders reached Mr. Fielding on the phone, and said she was told that the president would never knowingly keep a spouse abuser in a top job but that this was a private dispute in which nothing had yet been proven. Mr. Fielding then summoned Mr. Fedders. "We're not triers of fact," Mr. Fielding told the Journal, adding that there are always two sides to any domestic- relations dispute.

We can understand the hesitation of an experienced lawyer to prejudge the case -- a case going to divorce court -- of a troubled administration appointee who by all accounts was doing his work well. Still, it is not clear why considerations of fairness and delicacy had to keep Mr. Fielding from checking more closely into a shocking allegation which, if true, was bound to be deeply embarrassing to Mr. Reagan and evidence that Mr. Fedders was the kind of man who had no place in this or any administration.