The no-bill notices could also help fill a blind spot for policymakers examining the work of federal prosecutors, said Robert Weisberg, a Stanford University law professor.

The highest number of no-bills in the last decade the Bureau of Justice Statistics published such data came in 2007, when grand juries declined to indict 23 times out of 68,413 criminal cases commenced by federal authorities.

“If this is making a public record of potential incompetence or abusive uses of the grand jury, then it makes it possible for Congress to look at this stuff as part of its Department of Justice oversight,” Weisberg said, adding that if numbers pile up in a jurisdiction, a US attorney could be called before Congress or chief judges could seek explanations.