The Supreme Court has acted to protect the government (the executive branch of government, that is) from the ravages of old age, and the dangers of senility in high places.

What the court did was uphold the right of the Congress and the State Department to force foreign service officers into retirement for the crime of becoming 60. The idea of old people having important jobs! Really!

The foreign service has had the 60-and-out rule for years now. The idea is that overseas assignments can be dangerous. And taxing and tiring to old-timers who, as a class, cannot hack it.

Fortunately for other high government officials, the fold-up-your-tent-at-60 edict does not have universal application. It does not, for example, cover some older ambassadors whose main qualification for high, important posts is showering dollars in the direction of the right presidential candidate.

Passing the threshold of 60 has not stopped many senior, but agile, members of Congress from indulging in foreign and domestic affairs of heroic proportions. Nor from circumnavigating the globe -- at taxpayer expense -- on fact-finding trips. Nor does it stop them at parties and receptions, although the same pace -- after 60 -- is deemed too rigorous for foreign service officers.

Some present and past FSOs (no doubt teetering on the brink of their dotage) have been fighting the mandatory retirement policy. They contend that it is class discrimination. And stupid.

The diplomats and ex-diplomats point out that the federal government has abolished mandatory retirement because of age for most of its own jobs. And judges have torn their gowns in rage at age discrimination in other forms. And Congress has made it a federal rap for anybody -- but Congress -- to discriminate against anyone because of age.

There are people who might take a cheap shot at some legislators and judges. They might point out that the average age on the Supreme Court exceeds eligibility requirements for collecting social security benefits. The same types might crudely suggest that neither the Senate nor the House resembles Boys Town, or the local Jaycees.

If the 60-and-out rule applied to other branches of the federal service, we would have only one person on the Supreme Court. And he would have to quit on his next birthday.

Former Supreme Court justices have not been troubled by old age. Earl Warren was nearly 70 when he retired. Oliver Wendell Holmes was 81 when he stepped down. John Marshall of Virginia served as chief justice for 34 years, ending his service at age 79. Most of them didn't hit their judicial stride until after age 60. Happily, none of them chose the foreign service as a career.

If the same 60-and-out rule applied to the Congress, some of our leaders of the Senate and House would, even now, be in retirement homes in Massachusetts, West Virginia and other preserves for senior citizens. Fortunately for those who like to keep active, and working, those rules do not apply to them.

If the same 60-and-out rule applied to the Peace Corps, which has had its share of danger and hardship, some bureaucrat 10 years ago would have told Lillian Carter she was a little past it for duty in India, or anywhere else.

Luckily, the 60-plus ban in the foreign service has not always applied. Suppose somebody at the State Department had told applicant Benjamin Franklin, past 70 when he signed up to represent the colonies in France, to go back to Philadelphia and fly a kite?

Job Hunters Guide: There are more than a hundred federal hiring offices in this city and the odds are not even that the government has a complete list of all of them. But there is an updated guide available to those offices, their location and telephone number. It is called the Federal Employment Directory. It also includes tips for job hunters. Price by mail is $5.95, from Federal Employment Director Service, P.O. Box 34740, Bethesda, Md. 20034. Or call 340-2220 for information.