Hillary Clinton likes to quote Michelle Obama's campaign advice, "when they go low, you go high." But while she's put that motto on repeat, she hasn't necessarily put it into practice.

When attacked, Clinton retreats to the high road without explanation. But when she wants to attack, she charges into the gutter.

On Friday when news broke that the FBI reopened its investigation into her email server, Clinton was true to form.

Donald Trump, of course, pounced on the news, making a legitimate argument about Clinton's credibility at his New Hampshire rally. While the crowd erupted in cheers and chants of "lock her up," the Republican egged them on saying that her scandal has disqualified her from entering the Oval Office.

But rather than offer a rebuttal, Clinton retreated to the high road to take pot shots at her opponent. She repeated her mantra at an Iowa rally, ignored the bombshell news, and slammed the Republican with old attacks.

A gloomy looking Clinton highlighted allegations of sexual assault against Trump, and even brought up his bankruptcies. She warned that Trump could make this the last presidential election ever and that he'd roll back the right to an abortion. But she wouldn't mention the emails, because for Clinton, the high road means getting as far away as possible from attacks on herself.

While attacks on Trump's character and indiscretions are valid, Clinton's approach to her own record is just a dodge. In the name of taking the high road, she evades an obviously important issue and leaves the public in the dark. Whether or not the electorate will let her get away with it remains unclear.

The bounce-back of the email probe has thrown the race into flux. Clinton leads Trump by 6 points, but that advantage could still evaporate in the next 10 days. Minus a new scandal, the FBI investigation will dominate the news cycle. And if she fails to address the issue, she risks allowing her campaign to fall apart in the final stretch.

For the first time, a Clinton scandal has finally overshadowed one of her opponent's. Ironically, Clinton might have boxed herself in with her own strategy. Quick hits against Trump's character can't fix the scandal because she's already used them all, the same way Trump's attacks on Bill Clinton can't wash off allegations about his own misbehavior.

Approaching peak Trump, an electorate won't be satisfied by new lines about old scandals. They want to know about her inbox, and she has to offer a robust rebuttal.

If she doesn't, Clinton's White House dreams could crash while she's running between the high and the low road. And if she falls this time, she might not be able to get back up.

Philip Wegmann is a commentary writer for the Washington Examiner.