As the Senate wades into the murky legal job of putting President Clinton on trial, little is clear about the rules and procedures last used against a chief executive 130 years ago.
But if a full trial should go forward - and that is a big "if" - scholars and congressional experts agree on two points: First, it is likely to last months, not weeks. And second, the Senate will face major hurdles to accomplishing other work during a trial.
"Three weeks is completely unrealistic," says political scientist Betty Glad, referring to Senate majority leader Trent Lott's time estimate offered earlier this month. "They have to meet from noon every day, so that would make it very difficult for them to work" on other matters, says Ms. Glad, from the University of South Carolina in Columbia.
The anticipated burden of a drawn-out trial, both on senators and the public, adds to pressure on the Senate leadership to strike a deal with the White House that would abort the process.
Moreover, few believe the Senate could muster the 67 votes required to convict Mr. Clinton.
Yet on the other hand, many House Republicans are eager to see the trial go forward, making it harder for the Senate to abruptly halt the process - as it could, for example, by simply voting that the charges are not impeachable. "That would be a huge slap for their brethren in the House," notes Barbara Sinclair, a Congress expert at the University of California, Los Angeles.
Predicting how the Senate will act is further complicated by the unique nature of the nation's most elite legislative body: While less partisan and impulsive than the House, the Senate is more decentralized. By granting more power to its 100 individual members, the Senate is less likely to act as a team. "The [Senate] leaders really have the proverbial herding-cats job," says Ms. Sinclair.
Yet if a full trial does go forward, an unwieldy, time-consuming process is virtually guaranteed. Here are a few reasons:
* Lack of precedent. In US history, there have been only 13 impeachment trials, including just one of a president, Andrew Johnson, who was acquitted in 1868. So the precedent is minimal. Moreover, unlike court rulings, impeachment trials do not establish formal precedents for those that follow, making each one a new product of a unique political environment, scholars say.
* Rules subject to change. The Constitution provides only a broad outline of a presidential impeachment trial. In addition there are 26 Senate rules governing impeachment, first drafted for the Johnson trial, that provide more detail. Yet many of these rules may theoretically be changed if the Senate votes to do so. They were updated after the 1974 Watergate scandal.
* Greatly varying trial lengths. Most Senate trials have lasted several months, although the shortest took only 34 days, and the longest consumed more than a year. The trial of Johnson, in which he escaped conviction by one vote, lasted 74 days.
The sheer importance of impeachment, described by the Senate as "the most awesome power of Congress," is also likely to add to a trial length. The following is a thumbnail sketch of the main actors and course of events:
* The president. Clinton would not be required to attend the trial, and Johnson did not do so. His lawyers would have several weeks to prepare for a trial, as part of what some scholars anticipate could amount to months of pretrial activity.
* The prosecutor. The House of Representatives is the prosecutor, and its 13 appointed "managers," led by Rep. Henry Hyde (R) of Illinois, would make the case against the president.
* The judge. Supreme Court Chief Justice William Rehnquist would preside over the trial. He could be overruled on any matter by a majority vote of senators, but if a tie occurred, he would cast the tie-breaker.
* The jury. Senators, who under current rules must remain silent during the trial, would sit as the jury. They would deliberate behind closed doors, with strict time limits placed on how long each could speak.
The Senate could ease its workload by appointing a special evidentiary committee of 12 senators. This committee would hear the evidence and develop a trial record for other senators to consult at their convenience.
Such a step, taken in past impeachment trials for federal judges, could considerably "increase the speed and efficiency" of a trial, according to Buckner Melton, a professor at the University of North Carolina at Chapel Hill.
A majority of senators could vote at any point to dismiss the trial. This is how a plea bargain might occur. The Senate would agree to dismiss the trial if the president accepted another punishment such as censure.