It is impossible to tell the good guys from the bad guys in choosing socially responsible pension fund investments, according to a national authority on pension fund management.

There simply is not enough conclusive data, Roy A. Schotland of Georgetown University Law Center said. And different firms have their worst points in different areas, he said.

"The choice appears easy if a group critical of investments cares only about certain things they don't like, but you have strange inequities," Schotland told an employe benefits trust workshop of the American Bankers Association recently.

"Some, for example, are unwilling to accept any firm with South African involvement, but say it is all right if a firm pollutes like crazy," he said.

The critical groups vary so widely that they should not be allowed to jeopardize basic retirement security of a pension plan, which in itself is a social good, Schotland said.

Sensible judgment, not inflexible restrictions, should govern investment choices, he said. A large number of state and local pension funds were barred from buying common stocks and missed the great gains of the 1950s and 1960s, he said. Their emphasis on fixed income investments meant the effect of inflation has been "murderous," he said.

Today, many pension funds already are involved in socially responsible investment, such as federally guaranteed mortgages, he said.

All state and local pension fund boards should have employe, retiree and "neutral" (those with no personal stake in the investment) representation, Schotland said.

Pension management agreements should be revised so that proxy votes are exercised not by the trust department but the plan participants, he said. This would reduce the concentration of proxy voting power.

In discussing pension investment critics, Schotland and CorporateDate Exchange of New York is a watchdog group that has pointed out 99 so-called bad guy companies that do not meet its standards in these areas (unionization, equal employment hiring, health and safety or South African involvement.)

"Apparently, this group thinks that any nonunionized company is inherently bad, and completely overlooks other problem areas that others single out," Schotland said. "You just can't speak in absolutes when evaluating investments."