When the Senate Judiciary Committee kicked off its hearings on white-collar crime last Thursday, Sen. Joseph R. Biden Jr. (D-Del.) told the audience that "if you're looking for fireworks, it's going to be pretty dull."

He was right.

Anticipation had been building since the panel announced in November that it would hold a series of hearings on the Justice Department's handling of a spate of well-publicized criminal cases. But like a candidate whose handlers want to play down his chances of winning the next primary, Democratic Senate aides went out of their way to soft-pedal the hearings.

One of them told reporters "to lower your expectations. If you expect a piece of red meat a day and that we'll come up with 25 smoking guns about investigations the department didn't do right because they're either incompetent or corrupt, that's not what it's all about. The objective is not department-bashing . . . . It may not be the kind of thing you'd want to put on national television."

What was going on? With such juicy targets as General Dynamics, General Electric and E.F. Hutton, why were these hearings not quite ready for prime time?

Most congressional hearings are theater; they dramatize, rather than illuminate, the issues. The questions and answers are written in advance. The lawmakers, knowing what the witnesses are going to say, wait for opportunities to denounce, to contradict, to make their points in 15-second bursts suitable for network viewers.

In this case, however, ranking Democrat Biden decided to take the high road. For one thing, minority members don't have the staff to perform a real investigation; they haven't requested a single Justice Department document.

Biden is currently busy touring the country and testing the waters for a possible campaign for the 1988 Democratic presidential nomination. Some say he wants to seize the crime issue without appearing to be too strident.

"I think his intention is to develop the Joe Biden Comprehensive White-Collar Crime Control Act of 1986," a Senate aide said.

Committee Chairman Strom Thurmond (R-S.C.), who agreed after some negotiation to hold 10 or 12 hearings, could hardly be expected to attack the Reagan Justice Department. But if the Republicans maintain their hold the Senate in the November elections, Thurmond is expected to succeed retiring Sen. Barry Goldwater (R-Ariz.) as chairman of the Armed Services Committee, and spotlighting defense procurement fraud would be a good start.

When the first session got under way in the Dirksen Office Building, Biden lauded Thurmond for calling the hearing. Known for his soul-searching, rambling monologues when the subject is Edwin Meese III or William Bradford Reynolds, Biden was surprisingly restrained.

"It would be awful easy for us to engage in our own version of a witch hunt," Biden said. "We could insist on subpoenaing everyone in the world, we could demand documents. We'd undoubtedly attract a lot of press and make a lot of headlines."

But it would be wrong. "This is a cooperative effort . . . a bipartisan process," Biden said.

Sen. Howard M. Metzenbaum (D-Ohio), the panel's leading liberal flame-thrower, was the only one having no part of the statesmanlike approach. Metzenbaum listed the drug companies he plans to pursue for "corporate crimes of violence," and he accused the Justice Department of having "a two-tiered system of justice" that is soft on corporate lawbreakers.

Metzenbaum twice stopped his opening remarks because Biden was chatting with an aide. "I don't mind you not listening," Metzenbaum said. "I just don't want you talking louder than I am."

For the Justice Department, the hearing was a rare chance to tout its record. "We think we're doing a good job in this area, but we're always backpedaling," a department official said.

It was no accident that Deputy Attorney General D. Lowell Jensen showed up with an inch-thick compendium of successful white-collar prosecutions, along with 51 pages of prepared testimony.

Jensen agreed to summarize his statement and submit it for the record, but his opening remarks took 45 minutes. By that time, Thurmond and Biden were gone and only three of the panel's 18 senators remained.

When Metzenbaum's time had elapsed and he left the hearing, Sen. John P. East (R-N.C.) took the microphone. "I would propose -- I guess to myself, since I'm the only one here -- that we might take a recess of 10 minutes," he said