SENATORS TED STEVENS (R-Alaska) and Daniel P. Moynihan (D-N.Y.) are likely to get some flak for sponsoring the sudden move to defer, until 1983, the rule that would limit senators' outside earned income to 15 percent of their salaries ($8,250 per year). Instead, these two men and Senate Ethics Committee chairman Adlai E. Stevenson III (D-Ill.) should be commended for bringing this issue out of the cloakrooms and being willing to explain why they favor suspending a rule that they voted for two years ago.

We think they're right -- and that reflects some rethinking of our own. In 1977 we too supported the 15-percent rule as part of the stringent ethics codes that the Senate and House adopted, after much turnoil, in tandem with their pay raise from $44,600 to $57,500. We saw this as a package that would give members of Congress more adequate incomes, reduce the likelihood of conflicts between official and outside activities, and promote public confidence in Congress' capacity for self-discipline.

Since then, we, like many others, have grown more and more concerned about the smothering effect of too much righteousness and rules of conduct and disclosure that require people in public service to give up too much. The 15-percent limit on legislators' earnings, which took effect this year, is near the top of that list. It is more stringent than concerns for conflicts of interest or institutional seemlingess justify. It gives too little flexibility to lawmakers who need or want to augment their salaries and can do so without slighting the public's business.

We would nor rush to the opposite extreme and sweep away all curbs on legislators' outside activities. Nor has the Senate done so. Last week's action leaves intact the more sensible limits on speaking fees and honoraria -- $2,000 per appearance and $25,000 overall per year -- in the compaign law of 1976. As Sen. Stevenson emphasized, senators are still constrained by ethics rules that require full disclosure of outside earnings and prohibit the types of professional activities, such as practicing law, that are most likely to produce conflicts of interest. Those safeguards are surely enough to protect what Sen. Stevens called "the public interest in honest senators." Moreover, if a senator does exploit the higher limit by spending too much time on the lecture circuit, he is likely to hear about it from his constituents, who are the ultimate judges of senatorial conduct in any case.

Some problems with the public may yet flow from the way the Senate's action came about. Unhappiness with the 15-percent rule is widespread. Yet the subject was thought too sensitive for normal processing through public hearings, committee action and a roll-call on the floor. Instead, the Stevens-Moynihan measure was introduced Wednesday evening and passed by voice vote Thursday noon with few senators on hand. Three spoke for it. Three were present to object; three more put statements of opposition in the Congressional Record later that day. Nothing has been heard from the others, including more than 40 who voted for the rule two years ago. Their shyness may feed public suspicions that the Senate is doing something sneaky and untoward. We hope the House will be more straightforward when the issue comes up there.