THE SUPREME COURT heard argument Monday on a case that could have a profound effect on American working women and on the pension industry. At issue is a pension system that, in some cases, provides smaller monthly benefits to women because women, as a class, live longer than men.

Most working Americans who are covered by employer pension plans are guaranteed gender-neutral defined benefits when they retire. The federal employees plan is a good example of this kind of benefit. Each employee can figure out just what he or she will receive per month, based on salary and time worked, and benefits are the same for men and women. Some workers, however, are covered by defined contribution plans. In these cases, an employer makes the same contribution for each worker, but that does not always buy the same protection for men as for women.

In the case before the Supreme Court, the plaintiff, Nathalie Norris, worked for the state of Arizona, which provided equal contributions to a pension fund for each employee. Upon retirement, the employee could choose among three options: take all the money in a lump sum, take the money in monthly payments over a fixed period of time, or have the state buy an annuity that would pay a monthly amount as long as the retiree lived. It is the third option that is at issue; here, the same amount of money buys a smaller monthly benefit for a woman because actuarial tables show that she will probably live longer than her male coworker.

Is there really employer discrimination here--forbidden by Title VII of the 1964 Civil Rights Act--or is it discrimination by insurers? Are the insurers agents of the employer? Does it make a difference that Miss Norris could have accepted a lump sum or gradual payment from the pension fund, both of which are gender-neutral, instead of an annuity? But at bottom, we have an important social question: is it fair to pay a female retiree a smaller monthly benefit than her identically situated male colleague simply because, as a class, women outlive men?

The justices may well believe such a policy is not fair, but that it is entirely legal. Congress, on the other hand, makes policy and writes new law. If gender- based pensions are unfair and Congress decides to prohibit them, hard questions must be faced. Who will be covered--those already retired or about to retire or only those who start work today? If pension plans must provide increased benefits to women--benefits that have not been anticipated--who will be responsible for unfunded liabilities--employers, insurance companies, taxpayers or current workers? What about other gender-based insurance tables that favor women--life and automobile insurance, for example?

It is unlikely that the court will decide all these questions in the Norris case, but Congress will surely have to grapple with them in the months ahead. President Reagan has promised to end pension discrimination, and an increasing number of women in the work force demand action. Still, the details of establishing and enforcing new social policy are complex. A carefully crafted legislative solution would be best.