Until about 10 days ago, Attorney General William French Smith was one of the least visible members of President Reagan's Cabinet. For weeks, his press coverage consisted mostly of reports of parties he attended.

Then a couple of stories described the slow pace at the Justice Department and, suddenly, Smith came out of the shadows.

A week ago Thursday he had a news conference and urged repeal of the special prosecutor law. The next day he made a major speech signaling a shift in civil rights policy away from busing and racial quotas, and appeared on public television's MacNeil-Lehrer show.

The other day he invited several regular Justice Department reporters into his private dining room for breakfast. Next week he'll be touring Border Patrol facilities near San Diego and visiting the Los Angeles Times editorial board.

Aides say much of the flurry of activity was planned all along, but they acknowledge that they wanted their boss to speak out more to counter what they consider a mistaken impression that he isn't actively running the department.

Smith said as much to the reporters: "I gather the impression on the outside is that we're not doing anything."

The low-key, silver-haired Smith was stung especially by a short piece in a recent issue of Business Week magazine, which quoted unidentified White House officials as saying things like "He has no known view on any issue," and referring to him as a "somnambulist."

Smith joked at the breakfast that he hadn't found anyone in the White House who could pronounce the four-syllable word for sleepwalker, and added that the only thing he found accurate in the story was "the spelling of my name." He denied that the White House was running his department.

His aides acknowledge, however, that the perception of inactivity by their boss was heightened by several factors. Early claims of Cabinet government envisioned Smith Spending considerable time away from the department.

The choice of Edward C. Schmults, an experienced government lawyer, as his deputy, and Smith's refusal to take positions on key issues in congressional hearings and at press appearances added to the image that he wasn't in charge.

One press room wag recalled the "Maximum John" nickname of Watergate Judge John J. Sirica and said he thought of Smith as "Minimum Bill."

One Justice Department attorney who has dealt with Smith, but is not a hand-picked aide, said he felt the "public perception of the man is not the man. In private, he's got a good sense of humor, and he asks the right questions.

"His problem is that he's been a private adviser, the kind of lawyer who for 30 years made a lot of money and didn't get his name in the paper a lot. That's how some people measure success. He's just not used to being a public figure."

Smith's spokesman, Tom DeCair, said the 63-year-old attorney general hasn't been able to make more public appearances until recently because he's been busy interviewing lawyers to head his litigating divisions, and studying lists of nominees for judgeships and U.S. attorneys.

At 9 each morning, Smith meets with a handful of top subordinates, including schmults, Associate Attorney General Rudolph W. Giuliani, legal counsel Theodore Olson, counselor Kenneth Starr and DeCair, to discuss pressing business.

Smith has reviewed several civil rights cases, as well as the recent indictment of some Immigration and Naturalization officers who allegedly beat Cuban refugees at Fort Chaffee, Ark.

He also reviewed the decision not to accept a plea bargain offer from John Hinckley Jr., who is charged with trying to assassinate Reagan.

Smith said he also has been busy considering decisions in these areas:

Task forces on violent crime and on immigration and refugee policy. Smith has given top priority to these volatile issues, though some have questioned whether the federal government can have much impact on street crime.The Law Enforcement Assistance Administration was junked by the Carter administration after it poured billions of dollars into local police forces over the past decade without noticeable success.

The violent crime task force is expected to submit interim recommendations in mid-June.

The group studying immigration policy should forward a report to the White House in a few weeks on such sensitive questions as amnesty for illegal aliens, sanctions against employers who hire them and how to handle crises like last year's flood of Cuban and Haitian refugees.

A sweeping new approach to civil rights enforcement. In his speech to the American Law Institute, Smith said the department will continue to attack segregation, but would reject busing and other mandatory remedies.

He also told state and local prison officials last week that they wouldn't be held to strict new federal prison standards developed by the Carter Justice Department.

The civil rights community will be watching for the first cases that will demonstrate the shift in emphasis. The administration position on extension of the Voting Rights Act also is considered to have great symbolic, as well as practical, importance.

What aides term his "Watergate over-reaction" package. Besides attacking the special prosecutor law as "unfair and wasteful," Smith also has advocated changes in the Freedom of Information Act, the Foreign Corrupt Practices Act and restriction on the intelligence community.

To critics, he and the Reagan administration seem determined to roll back needed checks on institutional wrongdoing.

For instance, at his recent news conference, he said he agreed with CIA Director William J. Casey's position of allowing unannounced searches of newsrooms for evidence of disclosing agent's identities. But he couldn't or wouldn't articulate a reason.

This troubled some department attorneys, because the attorney general is supposed to balance the impulses of the intelligence gatherers with a concern for constitutional protections.

The possible merger of the Drug Enforcement Administration into the FBI. This proposal has surfaced with several new administrations, but Smith and Giuliani have criticized the Carter administration harshly for what they view as lack of commitment to strong narcotics enforcement.

So far they have been carful not the attack DEA chief Peter Bensinger personally. Drug agency morale is said to be suffering because of the uncertainty of its future and the implied criticism of its performance.

The backlog of nominations. After a Washington Post story last week noted the administration's failure to fill long-vacant judicial posts, Smith went out of his way at the breakfast with reporter4s to announce that 76 judges, marshals and U.S. attorneys have been selected, pending successful FBI checks.

Only three U.S. attorneys and one marshal have been nominated, however