In 1971, Whitney North (Mike) Seymour Jr., then the U.S. attorney in Manhattan, went to federal court to argue the Nixon administration's unsuccessful suit to prevent. The New York Times from publishing the Pentagon Papers.

Attorney Powell Pierpoint, a longtime friend and colleague of Seymour, said that Seymour "represented the government like a good soldier, though I don't think he personally believed in the case. . . . He made a damn good argument out of a poor case. He presented the argument himself. That's the kind of fellow Mike is."

Seymour's appointment yesterday as independent counsel to investigate former. White House aide Michael K. Deaver drew wide-spread praise from those who know the 62-year-old attorney and former state senator.

"He is very tough but very fairminded," said Joseph E. diGenova, the U.S. attorney here. "He has all the requisite skills to do the job fairly. You couldn't have had a better choice."

"He's been through this before," said Rudolph W. Giuliani, who worked for Seymour in the Southern District of New York and succeeded him as U.S. attorney. "He's had to make difficult decisions in high-publicity cases, and therefore he'll make the right call."

As an assistant federal prosecutor in the 1950s, Seymour helped prosecute the most prominent racketeer in New York, Frank Costello, for income tax evasion. As U.S. attorney from 1970 to 1973, he established a public corruption unit, handled celebrated narcotics cases and prosecuted the Knapp Commission's police misconduct cases, a role that was dramatized in the book and movie "Prince of the City."

Seymour also won the indictment of former attorney general John N. Mitchell and former commerce secretary Maurice H. Stans on charges related to a secret $250,000 contribution to the Nixon reelection compaign by fugitive financier Rohert L. Vesco. They were acquitted.

The Yale Law School graduate, described as a "Javits or Eisenhower Republican," was less successful in politics. He sought the U.S. Senate seat held by Daniel Patrick Moynihan (D-N.Y.) in 1982, but lost the GOP primary.

Three years ago, Seymour left a top Wall Street law firm to join a two-partner "country" law firm on Park Avenue that dispenses legal assistance with a personal touch.

Seymour is an outspoken opponent of political action committees for what he calls their "sinister" effect on Congress. he is a founder of Citizens Against PACs.

Seymour's late father, Whitney North Seymour Sr., a former American Bar Association president, was consulted by the Justice Department in 1973 about the appointment of the first Watergate special prosecutor, whose investigation gave rise to the independent counsel law five years later.

Seymour wasted no time getting started on his new assignment; an assistant called The Washington Post yesterday and asked for copies of all its news stories on Deaver.