A former top Justice Department official is saying a "criminal charge is justified" against Hillary Clinton because it's become clear that highly classified information was discussed on her private email server.

"The simple proposition that everyone is equal before the law suggests that Mrs. Clinton's state of mind — whether mere knowledge of what she was doing as to mishandling classified information; or gross negligence in the case of the mishandling of information relating to national defense; or bad intent as to actual or attempted destruction of email messages; or corrupt intent as to State Department business — justifies a criminal charge of one sort or another," Michael Mukasey, former attorney general in the President George W. Bush administration, wrote in The Wall Street Journal Friday.

"[F]rom her direction that classification rules be disregarded, to the presence on her personal email server of information at the highest level of classification, to her repeated falsehoods of a sort that juries are told every day may be treated as evidence of guilty knowledge — it is nearly impossible to draw any conclusion other than that she knew enough to support a conviction at the least for mishandling classified information," he wrote.

But Mukasey questioned whether criminal charges will be brought, and put the onus on FBI Director James Comey.

"If no recommendation to charge is forthcoming, or if such a recommendation is made but not followed by the attorney general, what happens then?" Mukasey asked. "Would the public stand for it? My guess is not. However, my guess is also that we won't be put to that test because our public officials will do their duty."