Congress plunges back into illegal-alien issue. Lack of consensus on numbers makes it hard for legislators to agree

Like Brer Rabbit, Congress has bravely plunged back into one of the thorniest brier patches in this city: the illegal-alien issue. The whole alien problem makes many congressmen want to run away, like Brer Fox. But key members of Congress, risking a few scratches, insist this will finally be the year the brier patch is plucked of its thorns.

Several senators have spent this week polishing S 1200 -- a bill that for the first time would penalize American businesses that hire illegal aliens. The jobs issue has been one of the sharpest thorns in this debate. Meanwhile, House members have been crafting their own bill. The House, more sensitive than the Senate to the demands of Hispanics, wants to speed up the legalization of many of the aliens already in the United States.

Despite such progress, however, the issue is still seen as an impossible thicket by many in Congress. Tangled together are questions of jobs, wages, immigration quotas, language, culture, foreign affairs, a worldwide population explosion, and American traditions. Adding to the difficulty is the lack of hard data. For example, just ask a simple question, such as ``How many illegal aliens are currently in the United States?'' and you are likely to get a blank stare from many experts. Or an argument. Is the total 500,000? Two million? Five million? Ten million? Fifteen million? The fact is, nobody knows. Not Congress. Not President Reagan. Not the US Immigration and Naturalization Service. This uncertainty makes solutions hard to find, and it gets emotions pumped up on all sides.

Why are the numbers so important? First of all, there's the question of legalization. Just about every immigration bill would give legal status to many of the Mexicans, Filipinos, Koreans, and others who slipped into the country undetected during the 1960s and '70s. But no one is sure whether the numbers are in the thousands, or the millions. If it's millions, that could be a problem. Costs could skyrocket for welfare, schooling, indigent care, food stamps, aid to families with dependent children, and many other things. States like California, Texas, Florida, New York, New Jersey, and Illinois would be hard hit. Further, legalization would mean that these millions could eventually bring in millions of their relatives now living abroad. Without restrictions. In other words, it could set off a new population boom in the US. On the other hand, if the numbers are small, the US could probably absorb them, and their relatives, with little effort.

The confusion over the numbers of illegals can hardly be exaggerated. Just look at a few of the guesses now being bruited about in this city:

2 million to 4 million -- US Census Bureau.

5.6 million -- Congressional Budget Office.

3 million to 12 million -- Sen. Alan K. Simpson (R) of Wyoming, chairman of the Senate subcommittee on immigration and refugee policy.

6.5 million -- Alan C. Nelson, commissioner of the Immigration and Naturalization Service.

8 million to 10 million -- Delia Combs, assistant commissioner of the INS.

The debate over numbers was renewed a few weeks ago, when the National Research Council, at the conclusion of a two-year study, suggested that the number of illegals in the United States was probably only in the range of 1.5 million to 3.5 million. At the same time, the study conceded: ``No range can be soundly defended.'' What really surprised many experts in this field, however, was this conclusion in the study: ``There is no empirical basis at present for the widespread belief that the illegal-alien population has increased sharply in the late 1970s and early 1980s.'' This shocked some experts, who note that arrests of illegals, especially along the 2,000-mile US-Mexican border, have surged, from only 110,371 in 1965 to more than 1.2 million a year in both 1983 and '84. The research-council study says this shows only that ``the efficiency of the Border Patrol has increased.'' In fact, the study said, ``the population [of illegals] has increased little if at all since 1977.'' Immigration expert Michael S. Teitelbaum, who is now with the William P. Sloan Foundation in New York City, calls such conclusions by the research council ``unfortunate.'' The important thing for the country, Dr. Teitelbaum says, is to get better data on the problem, not to make additional guesses.

The uncertainty of the numbers hangs over the work pushing forward on Capitol Hill and could snag it. That's what happened last year. The White House became concerned about the possible costs of legalizing millions of aliens. Some House members, such as Rep. Hal Daub (R) of Nebraska, fretted about the millions of relatives of illegals who might suddenly pour into the country after legalization. Even so, there is movement. In the upper chamber, Senator Simpson, the leading force on Capitol Hill for immigration reform, has been carefully adjusting the language in S 1200 to bring aboard additional support. In the House, perhaps as early as today, Judiciary Committee chairman Peter W. Rodino Jr. (D) of New Jersey will unveil his own, more liberal bill. The big difference between these bills will be their stance on legalizing aliens already in the US. The Simpson bill would delay legalization until the US regained control of its borders. As long as the borders are leaking like a rusty radiator, there will be no legalization. The Rodino bill, according to one of his aides, will require legalization as soon as new enforcement procedures are put into effect. If Brer Simpson and Brer Rodino can work together, they may conquer that thorny brier patch after all.