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 L.A. and Portland, will go to trial this fall.

The dismal record has raised questions about rushed investigations and aggressive charging tactics by prosecutors under pressure to show the Trump administration is cracking down on people who assault law enforcement. It comes as the Justice Department is facing broader setbacks in politically charged investigations, with grand juries repeatedly refusing to return indictments and trial juries granting acquittals.

“Prosecutors tend to win because they control what cases they pursue and they have a lot of resources and discretion,” said Mary Fan, a former federal prosecutor and law professor at the University of Washington.

The fact that the government failed to win any felony assault convictions at trial calls into question “whether or not these charges should have ever been brought in the first place,” she said.