Willful negligence is an oxymoron.
If you’re negligent, you never intended for the injury or loss to happen to anyone. It’s usually because of an maliciousness lack of concern or responsibility.
Hillary’s use of an illegal and illicit method of hiding communications from the government is EASILY negligent on it’s face. You don’t even need to interview her to show negligence. You only need to present the physical evidence.
But I would suggest that the willful or intent part is easily provable case. You actually have to go way out of your way to do the things that she did to hide her email and transmit classified information. Nobody with several braincells to rub together would ever believe that you hire someone to buy and set up your own email server when you could get the service free and without effort from the government, then pay someone to manage it, and put it somewhere that it can’t easily be discovered, unless you INTEND for it to happen.
...because of an UNmalicious lack of concern... (negligence)
Need to take advantage of that preview better.