Judge Scalia seen as major force on Supreme Court. Formidable intellect and conservative philosophy mark Reagan appointee

Very bright, professionally able, personally charming. And a consensus-builder. That's the way legal scholars describe Antonin Scalia, President Reagan's newest nominee to the United States Supreme Court. Judge Scalia is now a member of the US Circuit Court of Appeals for the District of Columbia.

On issues, Judge Scalia is generally conservative; by itself his vote is not likely to change the balance of the Supreme Court. Through his considerable powers of persuasion, however, Judge Scalia may wind up altering the balance -- and thus the outcome of close decisions.

In reaching court decisions he is widely viewed as repeatedly seeking to ``try to find a middle ground,'' in the phrase of Judge Abner Mikva, a liberal colleague for four years on the Court of Appeals. He calls Scalia's approach ``collegial,'' and says the appointment ``is going to be good for the institution'' -- the Supreme Court.

Scalia ``will be far more capable of swaying the middle votes'' on the Supreme Court than retiring Chief Justice Warren E. Burger, says Bruce Fein in a freqently expressed comment. Mr. Fein is a legal consultant and an adjunct scholar at the American Enterprise Institute. As a result, say several legal experts, conservatives on the court may wind up turning 5-to-4 defeats into 5-to-4 victories.

Conservatives are delighted with the choice. ``Very good news,'' says Daniel J. Popeo, general counsel of the Washington Legal Foundation, who calls Scalia ``an articulate spokesman'' for conservative points of view.

Mr. Popeo says the nomination signals ``a new era that we are entering into in the Supreme Court.''

``They're going to interpret law, not make it,'' he says. ``The door is slowly closing for . . . the drug dealers . . . and for those who use the courts to accomplish a social agenda.''

Yet some scholars warn it would be a mistake to put Scalia down as a guaranteed vote for conservative causes.

``He is basically a very independent man,'' says Gerhardt Casper, dean of the University of Chicago Law School, where Scalia was a professor from 1977 to 1982 except for a year as visiting professor at Stanford.

Dean Casper describes Scalia as ``extremely bright.''

``He is a very tenacious intellect,'' he adds. ``He thinks things through and doesn't give up until he's thought them through all the way.''

The object of all this comment graduated first in his class from Georgetown University, and went on to Harvard Law School.

He has taught at the University of Virginia as well as at Chicago and Stanford. He worked several years in the Department of Justice, and has been a member of the US Circuit Court of the District of Columbia for four years.

Those who have worked with him say that, as Judge Mikva puts it, ``he's a delightful colleague.``

``He's got a great sense of humor,'' says Mikva. ``He's a good story teller. He's got a good sense of himself, he's not vainglorious.''

He's also a well-rounded individual, a jogger, tennis player, and family man. He's the father of nine children.

Upon his confirmation Judge Scalia will be the first American of Italian descent to be a member of the Supreme Court. President Reagan's previous court appointee, Sandra Day O'Connor, was the court's first -- and thus far only -- female member.

Some of Judge Scalia's views are highly controversial. He has criticized the Freedom of Information Act and upheld the right of the US Park Service to prevent demonstrators from sleeping in Washington parks.

But there is no disagreement about his intellectual capabilities. Both ideological friends and foes agree that these are formidable.

``He has written with great distinction,'' says Robert Katzmann, a lawyer and political scientist affiliated with the Brookings Institution. ``On the administrative and legislative process, his principal expertise is in administrative law.''

In a view with which others concur, Mr. Katzmann expects Scalia to zero in on legislative intent when rendering a judgment on a law.

As a judge ``acutely aware of the workings of the legislative and administrative . . . he will tend to write opinions which force Congress to say what it means,'' Mr. Katzmann says, rather than relying on congressional reports, drafted primarily by staff assistants, to spell out the intent behind the laws that Congress enacts.