He was a freshman in Congress, a quick-witted, tart-tongued southern conservative from the Republican stronghold of Roanoke. He'd come to the Hill on Richard Nixon's coattails in 1972, and if anyone could be counted on during the agonies of Watergate, it was surely Rep. M. Caldwell Butler. Or so many Virginia Republicans thought.

But in the steamy summer of 1974 Butler surprised them, announcing from his seat on the House Judiciary Committee that he would vote for Nixon's impeachment. "For years we Republicans have campaigned against corruption and misconduct . . . . But Watergate is our shame," he said. "I cannot condone what I have heard, I cannot excuse it, and I cannot and will not stand still for it."

Butler is retiring after a decade in Congress, and he leaves no less the maverick than he was when he came in. Recently, he set his sights on two of his own party's appointees.

Two weeks ago, two Republican directors of the Legal Services Corp. testified before an investigative subcommittee about the large consulting fees they charged the government in a program for the poor. Butler again smelled misconduct, and wasted no words in saying so: "It sounds like the first thing they did was put all four feet and a snout in the trough," drawled Butler. This time, no one was surprised.

After 10 years of watching Butler follow his own drumbeat, veering left on occasion to argue against a constitutional amendment banning busing and veering right most often to vote with his conservative Virginia compatriots, his House colleagues may not have always understood him. But they did know, as Rep. Barney Frank (D-Mass.) said, that Butler's actions over the legal services fees and Watergate were born of "the distaste he would have for people not living up to ethics."

Butler, a gangling man of receding chin and toothy smile, is a true Mountain Valley conservative. His voting record is staunchly pro-Reagan, and his views are deeply traditional, the stuff of the Shenandoah Valley where he was born.

He was one of the leaders in the battle against extension of the Voting Rights Act last year. Under the act, a civil rights measure passed in 1965 to ensure more blacks had an opportunity to vote in the South, Virginia must get clearance from the Justice Department for any change in its election laws. Butler said that although the act is a "monumental piece of legislation that has done a lot to improve" election procedures in his own state, it provides no incentive for states to "get out from under" the burden of reporting every law change to Justice.

Butler was one of a tiny band of House conservatives, including all of the state delegation except Northern Virginia Rep. Frank R. Wolf, to vote last year against the extension in a lopsided 389-to-24 roll call that followed months of heated debate.

Still, the 57-year-old Butler often could be found fighting on opposite sides from his Virginia colleagues. "I have probably been more on the liberal side on the abortion issue than the Virginia delegation . . . also on other social issues," he said last week reflecting on his years in the House. "It's not because I'm a liberal, a moderate or a conservative, but because I'm a lawyer."

Butler said he has not found "a satisfactory way for a right-to-life amendment" to meet constitutional requirements. He also has voted to allow the use of federal funds for abortions because he feels it is unconstitutional to "deny abortions, which are perfectly legal, to poor people . . . just because they are poor."

Butler began his political career more than 20 years ago in his native Roanoke when he ran successfully for the Virginia General Assembly and became the leader of a band of Republicans so outnumbered by the Democratic majority that they got appointed only to committees that never met.

Arthur R. (Pete) Giesen Jr., a Richmond colleague, recalled that their GOP group became known in Virginia as the "constructive obstructionists" for their fights against certain Democratic measures. Because the Democrats had a special advisory council -- a mainstay of the old Byrd machine, according to Giesen -- Butler had the Republicans set up a panel of their own, which traveled around the state holding hearings on such issues as election reform.

"Even then, Butler had his great wit and sharp tongue, and the media loved him," Giesen said.

Butler honed those skills in Congress, where his caustic wit was both a blessing and a curse. He was known as a "very demanding person, a perfectionist" who held high standards for himself and others and would sometimes turn his caustic tongue on those who didn't measure up.

But his humor could also be self-deprecating. When fighting a losing battle in 1975 for an amendment to the Voting Rights Act that would provide states such as Virginia with an escape clause, Butler dubbed his measure "the Impossible Bail-Out Amendment." Its requirements were so strict that many northern states would not have qualified, said former aide Kenneth Klee. Still, Butler argued it would provide some incentive for states to improve their minority voter participation.

When Butler came to the House in 1972, the Judiciary Committee was not his first choice of assignments. Yet it is on Judiciary that he made his name -- first during the Watergate hearings and later by working with Rep. Don Edwards (D-Calif.) to shepherd a massive and complex revision of the country's bankruptcy laws through Congress.

Last June, a portion of that law was declared unconstitutional and Butler spent his last days in Congress seeking passage of a compromise bill hat would have kept the system going. "He's trying to work, work, work," Edwards said a few days before the session ended. "But I think it's hopeless." The bill died after House and Senate failed to agree on a compromise.

One former aide said "few members will give themselves to issues like bankruptcy that are not politically sexy. Few have the willingness and the mental power. Butler has both."

During the Watergate days, Butler was one of the Judiciary Committee's "Fragile Coalition," a group of three southern Democrats and four Republicans who became the swing votes for impeachment. As the group worked to draft proposed articles of impeachment, Butler was the technician. "He was always the one saying, 'No, you can't use that word, it doesn't provide this. Or let's try the sentence this way,'" recalled a lawyer who worked on the drafting.

Now Butler has left Congress to practice law in Roanoke, partly for financial reasons -- he has sent four children through college and maintains two homes -- and partly because he believes it is time to go. "I am 57 years old, and if I'm going to have another career, the change would have to come in a year or two," he said in a recent interview. "I'm satisfied I don't want to stay here forever."

Some of those who don't share his political philosophy say Butler is the type of representative the House can ill afford to to lose. "If we have to have a conservative Republican around," said Rep. Robert Kastenmeier (D-Wis.), "it might as well be Caldwell Butler. He is a man of excellent mind."