Having been turned down by the Department of Commerce, proponents of "cooking" the 1990 census figures have taken their argument to the federal courts.

The plaintiffs claim that the government's decennial census under-counts blacks and Hispanics and they want the figures arbitrarily adjusted upward to account for those who allegedly are missing among these groups.The push for this proposal, as Scripps Howard News Service reports, comes mainly from those who would benefit. Big cities with large black and Hispanic populations would get more money from federal programs in which funds are distributed on the basis of census figures. New York City, for example, contends it loses as much as $50 million a year because its population is under-counted.

The Democratic Party would benefit, too. Seats in the U.S. House of Representatives, as well as those in state legislatures, are distributed primarily on the basis of population. If the Census Bureau were required to increase its figures for black and Hispanic neighborhoods, it probably would mean more seats with a Democratic orientation, since these groups are more likely to vote Democratic than Republican.

The Commerce Department, of which the Census Bureau is a part, was right to reject the proposal to "adjust" the 1990 figures. The decennial census required by the Constitution is to count heads. It is not supposed to be a political wet nurse.

It is not possible to find every single resident of the country at any given time. If some people are missed, it's usually because they want to be missed; they can be illegal aliens, or living in violation of local housing laws, or have some other reason for not wanting authorities to be aware of them.

To try to account for what has been called the "invisible Americans" would inject an undesirable political element into census taking.

The federal census is one function of government that most people feel is above suspicion. If the government begins to manipulate the numbers for political purposes, its reliability and usefulness will be diminished.