The examination, which included cases spanning the past two decades, found some with parallels to Clinton’s use of a private server for her emails, but — in nearly all instances that were prosecuted — aggravating circumstances that don’t appear to be present in Clinton’s case.

The relatively few cases that drew prosecution almost always involved a deliberate intent to violate classification rules as well as some add-on element: An FBI agent who took home highly sensitive agency records while having an affair with a Chinese agent; a Boeing engineer who brought home 2000 classified documents and whose travel to Israel raised suspicions; a National Security Agency official who removed boxes of classified documents and also lied on a job application form.

Clinton herself, gearing up for her FBI testimony, said last week that a prosecution is “not gonna happen.” And former prosecutors, investigators and defense attorneys generally agree that prosecution for classified information breaches is the exception rather than the rule, with criminal charges being reserved for cases the government views as the most egregious or flagrant.

“They always involve some ‘plus’ factor. Sometimes that ‘plus’ factor may reach its way into the public record, but more likely it won’t,” one former federal prosecutor said.