The possibility that the jury in the political corruption trial of Maryland Gov. Marvin Mandel might fail to agree on a verdict did not come as a surprise to area legal experts yesterday.

Although a deadlocked jury is an anathema to judges and prosecutors, it is a risk in any complicated case involving allegations of white-collar crime, according to University of Maryland law professor Abraham Dash. And as the number of white-collar crime prosecutions has increased, so has the number of "hung," or deadlocked, juries.

"Two things can happen," Dash explained. "One, it is so complicated that the jury is confused. They think that something happened, but they're not sure what and they can't agree.

"Also," Dash added, "you've always got the possibility of the lone holdout."

The principal that a single doubting juror can prevent a verdict is rooted deep in the beginnings of Anglo Saxon common law. From the 14th Century on, British law has stated that a verdict must be agreed to by all jurors.

This same principle of unanimity has been a part of American law since the framing of the Constitution.

However, in recent years the U.S. Supreme Court has permitted some state courts to accept verdicts that are not unanimous. Ten jurors can render a verdict in Oregon, even if their two colleagues disagree. In Louisiana, only nine jurors have to agree for a verdict to be valid.

In federal courts, however, the principle of unanimity prevails. When a jury is deadlocked, a mistrial is declared and the case is either tried again or charges are dropped.

Federal prosecutors in the Marvin Mandel case said yesterday that they had not fully discussed what course of action they will take if the jury cannot resolve the deadlock and fails to reach a verdict.

In a footnote to a 1971 decision affirming a split verdict in Oregon, the U.S. Supreme Court cited several theories for the origin for the idea of unanimity.

One idea was that the principle was developed to compensate for lack of other rules which would assure a defendant a fair trial.

Another possibility, the court said, was that the principle grew out of the ancient custom of adding jurors to a jury until there were 12 who supported a particular position. When this technique was abandoned, the requirement that one side obtain the support of 12 jurors remained.

In a detailed study of the issue, two lawyers found in 1971 that hung juries result in 5.6 per cent of the cases where unamimity is required and in 3 per cent where it is not. But for most judges a trial that ends in a deadlocked jury is a totally unsatisfactory proceeding.

So in order to avoid a deadlock, many judges from the early 1900s onward have given divided juries the so-called "Allen Charge," a set of instructions designed to prod the jurors into agreement.

The message that U.S. District Judge Robert L. Taylor gave the Mandel jurors yesterday after they reported their impasse was a modified version of this charge. He told them that ". . . after full deliberation and consideration of all the evidence, it is your duty to agree upon a verdict, if you can do so without violating your individual judgment and conscience."

In the Allen case, Alexander Allen was charged with murder in Arkansas in the late 1980s and stood trial three times.

At his third trial, when the jury returned to the courtroom to declare they were deadlocked, the judge sent them back for more deliberations declaring that "in a large proportion of cases an absolute certainly cannot be expected," and admonished the minority carefully to consider the reasoning of the majority.

Allen's subsequent conviction was appealed to the Supreme Court, which upheld validity of the charge. Although it has been a controversial issue in legal circles over the years, the Supreme Court has upheld the Allen Charge again as recently as 1955.