The U.S. Justice Department failed to secure felony convictions against most of the 102 protesters arrested in four major cities last year on charges of assaulting federal authorities — a record far below the norm in federal assault prosecutions.

All of the dozen cases that made it to trial, mostly in Los Angeles, ended in acquittal, mistrial or dismissal. Experts say that’s surprising for a department known for its ability to win at trial. The last three felony assault cases, in LA and Portland, will go to trial this fall.