Federal judges across the nation are shouldering criminal caseloads that vary widely in size, sometimes even among judges in the same courthouse, according to a new study.

The study by the Transactional Records Access Clearinghouse, or TRAC, at Syracuse University found three courthouses where the judge with the largest criminal caseload had sentenced more than twice the number of defendants as the judge with the smallest caseload from October 2006 through July 2012. They were Los Angeles; Beaumont, Texas; and Camden, N.J.

Overall, the study found 18 courthouses where the heaviest sentencing load was at least 1.4 times larger than the smallest.

The study, release Sunday, was made possible because the clearinghouse, which uses the Freedom of Information Act to collect criminal justice data, earlier this year assembled the first publicly available database of sentencing records, sortable by judge.

Judges in the courthouses with the widest disparities cited unique local circumstances to explain the differences.

David Sellers, a spokesman for the administrative office of U.S. courts, said he wasn't surprised or concerned with these findings. He noted, however, that the judiciary needs more judges, particularly along the Southwest border.

That appeal for more judges was buttressed by another finding of the study that documented a more widely known disparity in criminal caseloads between districts in different regions. These regional differences are driven by the large number of immigration cases along the Southwest border where judges have long complained they handle too many cases to give each one proper consideration.