With the government just two days from resting its criminal conspiracy and bank fraud case against former budget director Bert Lance and three others at U.S. District Court here, presiding Judge Charles A. Moye Jr. today abruptly halted testimony.

After dismissing the jury until Friday, Judge Moye requested oral arguments Thursday from attorney on both sides on a key element of the government's case: the conspiracy count. The surprise adjournment followed an early-afternoon meeting in chambers between Moye and attorneys. The judge ordered the attorneys not to divulge to reporters what was discussed.

But Moye did say that the oral arguments Thursday concerned the conspiracy count, and he added: "I think the ruling may be the key ruling in the case."

During the 2-week trial, Judge Moye has occasionally suggested that the conspiracy count needed to be assessed in light of some Supreme Court decisions.

In particular, the judge has cited the Kotteokas decision in the mid-1940s.

That decision, as in the Lance case, involved a conspiracy with a central figure and several co-conspirators. The government had argued that the central figure was the hub of the conspiracy and the co-conspirators were spokes. The government said the conspiracy was the rim of the wheel that joined the defendants.

But the high court concluded that there were eight separate conspiracies, not a single one as the government had contended.

In that case, the court also ruled that a particular defendant in the conspiracy had been prejudiced by evidence against other defendants.

Similarly, in the Lance case, attorneys for some of the defendants have argued that their clients have been dragged together unfairly by the government in an attempt to justify the conspiracy count.

Besides Lance, the defendants charged with conspiracy are Thomas M. Mitchell, who handled Lance's business affairs while he was in Washington as Carter's budget director; Richard T. Carr, a one-time northwest Georgia banking associate of Lance; and H. Jackson Mullins, a former druggist in Lance's home town of Calhoun who purportedly lent his name to a variety of Lance's alleged financial manupulations.

The conspiracy count accused the four defendants of making false statements to bankers and overvalued financial statements to get loans, willfully misapplying bank funds and misleading government examiners through false bank statements. The case involves some 41 banks, most of them in northwest Georgia where the defendants live.

The conspiracy allegedly began in 1970 when Lance headed Calhoun's First National Bank, and continued into the mid-1970s, when he headed the National Bank of Georgia in Atlanta. The government contends the conspiracy went on for the nine months Lance was budget director beginning in January 1977.

Besides conspiracy, the government charges the four defendants in separate counts with falsifying bank records, misapplying bank funds and filing false financial statements to get loans.