"BIENNIAL TORTURE" IS how one political observer described Abner J. Mikva's last four campaigns for Congress in Illinois' 10th district, in the affluent suburban area along Chicago's north shore.

Mikva, a persistent reform Democrat during the heyday of Chicago machine politics and now a nominee for the federal appeals court here, spent two safe terms representing the urban, liberal southside 2nd District until it was reapportioned out from under him in 1971.

When Mikva moved to the newly created 10th, critics called him a carpetbagger, and his Congressional campaigns turned into little wars. He lost the first and then won three very expensive, exhausting and narrow victories over his Republican opponents.

Mikva, 53, said he began to feel like a rubber band that has been stretched too many times. During an interview in his office Friday afternoon, he said he had told his family members that he probably wouldn't run again. He was having trouble, he said, "revving up" for the campaigns.

"I really do feel people ought to change direction after a certain period of time," Mikva said.

During five terms in the Illinois legislature and five in the U.S. Congress, Mikva was an effective advocate for classic liberal issues. In the state house, he pushed the rights of welfare recipients and the mentally ill, emphasized consumer and environmental protection, helped draft ethics legislation and worked hard to reform the state criminal code.

In Congress, he opposed increased military spending and pork-barrel water projects, favored public financing of congressional campaigns, was a key member of the influential Ways and Means Committee, stubbornly introduced a stiff handgun-control bill each year and was a leader in the effort to rewrite the federal criminal code.

Abner Mikva, an honors graduate of the elite University of Chicago Law School, clerk to U.S. Supreme Court justice Sherman Minton, successful lawyer and law instructor, has been a busy aggressive legislator for more than two decades.

There is limited opposition to his appointment from conservatives, who fear that Mikva the judge won't be able to separate himself from Mikva the legislator, and more vigorous protests from the National Rifle Association, which considers him nothing less than an archenemy because of his unyielding support of handgun control. Nevertheless, there is little doubt that Mikva, who over the years has gained the respect and admiration of Democratic and Republican leaders in the House and Senate, will get his seat on the prestigious U.S. Court of Appeals here.

There is an aura about this federal appeals court, an atmosphere of nationwide influence. It is often described as second in importance only to the U.S. Supreme Court. And it has earned a healthy reputation for liberal and imaginative opinion making, particularly in the area of criminal law.

In recent years, however, since the bulk of criminal cases were transferred to the local courts, the federal side has been increasingly involved in massive, complicated cases brought directly to the appeals court from federal regulatory agencies, such as the Federal Trade Commission, the Federal Energy Regulatory Commission and the Federal Communications Commission.

These cases affect the way Americans live, what drugs they find on store shelves, how radio and television broadcasting will be regulated, how utility rates will be set and how the quality of the environment will be protected. It is estimated that the United States government is a party on one side or another to about 80 percent of the court's cases, which also include civil rights and employment discrimination cases, claims for access to government records through the Freedom of Information Act, and resolution of labor disputes.

President Carter's selections of Mikva and former assistant U.S. attorney general Patricia M. Wald to fill two new seats on the appeals court marks the first changes in the nine-member bench in almost 10 years. Three of the court's present members were appointed by President Nixon, three by President Johnson and two by President Kennedy.

Carter will get a third opportunity to make an appointment to that influential court, and maybe more, giving the Democratic president an extraordinary hand in reshaping the bench.

Former Chief Judge David L. Bazelon, nominated by President Truman in 1949, last month assumed the semi-retired status of senior judge, making his seat available to a new appointee. In addition, three of the court's current members - Judges Edward Allen Tamm, George E. MacKinnon and Roger Robb - are all more than 70 years old, making them eligible for retirement. All have served the 10 years necessary to qualify them for full retirement benefits.

Chief Judge J. Skelly Wright and Judge Carl McGowan are both over 65 and have served on the court more than 15 years, making each eligible for senior status. None of the judges, however, have indicated publicly that they are thinking about retirement.

The possibility of great change in the court's composition and the loss of the criminal cases, where the liberal and conservative lines were clearly drawn, makes it difficult to predict what Mikva's role will be as an appeals court judge. No doubt, Mikva and Wald will both contribute to the liberal strength of the court, which has lately taken a more conservative stand.

As a novice on a court that has been criticized for backlogs and overly long opinions, Mikva's greatest contributions from the start may be his undisputed reputation for hard work and his ability to cut through complicated questions to the heart of an issue.

And on the fifth floor of the United States Courthouse, where the often volatile personalities of the appellate judges clash, the soft-spoken gentleman from Illinois may be a welcome conciliator.

Steven P. Frankino, dean of the Creighton University Law School in Omaha, Neb., from 1971 to 1977, has been apointed dean of the Columbus School of Law at The Catholic University of America here and general counsel to the University. Frankino, 43, who succeeds John L. Garvey, earned both his undergraduate and law degrees at Catholic and was a member of the law school faculty there and at Villanova University before he was named dean at Creighton. Frankino is currently a partner in Kutak, Rock and Huie in Omaha. Garvey will return to research and teaching at Catholic.

OBITER: Timothy B. McBride and Charles W. Surasky are now associates at Shaw, Pittman, Potts and Trowbridge, and J. Patrick Hickey recently returned to the firm after serving as director of the city's Public Defender Service.... NBC law correspondent Carl Stern will address a luncheon meeting of the Washington Council of Lawyers Wednesday. His topic: "Is the Press Getting a Raw Deal from the Courts?" CAPTION: Picture, Abner J. Mikva is nominee to U.S. Appeals Court. By James K. W. Atherton - The Washington Post