The American Bar Association today opposed a controversial Justice Department proposal that would allow prosecutors to appeal lenient sentences.

Though the association cited "government tyranny" and the rights of individuals as the primary reasons for opposing the proposal, the lawyers' position against it was pushed most vigorously by corporation and banking attorneys here.

The proposal is part of the comprehensive criminal code revision under consideration in the Senate.

Philip Heymann, assistant U.S. attorney general in charge of the criminal division, flew to Chicago today to lobby for the government position. He told the lawyers it was a matter of "public perceptions of what justice is in the United States."

He cited, among other cases, a recent sentence of three months' probation imposed on the corporate perpetrator of a $27 million tax fraud as the kind of situation where the government might want to appeal.

The provision of the code would establish a sentencing commission to set guidelines for maximum and minimum punishments for specific crimes. Under the bill, the government would be able to appeal a judge's sentence that was lower than the minimum, so long as the appeal was approved by the attorney general and the solicitor general.