AGENCIES GO to great and occasionally unseemly lengths to please influential members of Congress. Sen. Roger W. Jepsen, chairman of the Armed Services subcommittee on manpower and personnel, has the Navy's cooperation in developing this art in new directions.

Marine Lt. Col. James E. Secrist is assigned to the senator's personal staff, where much of his work involves helping Iowa companies trying to do business with the Pentagon. This is comparable to the traditional help members and their personal staffs give to constituents facing the impenetrable bureaucracy--a problem with a Social Security check, a city's application for a HUD grant, and so forth. In fact, help with procurement problems is common. It's all called casework. Competing for shares of pork barrel programs is casework on a grand scale. Purists argue that casework should not be financed through members' personal staff budgets or other public funds because of the substantial political benefits to the incumbent. On the other hand, it is a public service arguably deserving taxpayers' support. Close questions abound--for instance, what about congressmen's free use of the mails for self-promoting newsletters to the constituency? But on balance, everyone tolerates casework.

Assigning executive branch personnel to such duties is an abuse of that tolerance. It circumvents the visible, limited staff budget and offers opportunities for favoritism in both directions. Which agency will a powerful chairman favor with a slot on his staff, and which senator will the Navy favor with a little extra staff help? True, executive personnel are on rare occasions detailed to work on the Hill. They can be valuable experts, and can take a valuable perspective back to their agencies. The likely benefits would outweigh the potential for abuse if Col. Secrist were clearly freed of ties to the department for a set time and assigned to work as a military expert on a committee staff isolated from personal casework or partisan efforts. Sen. Jepsen's arrangement appears to fail on all counts.

Iowa ranks near the bottom of all states in share of Defense Department spending, and Mr. Jepsen faces a tough reelection battle. His concern for constituent services is understandable, but his solution shows poor judgment. And the Navy is wrong to cooperate.