The State Department has finished its review of the more than 30,000 emails that former secretary of state Hillary Clinton had kept on her private server and turned over to the State Department for review prior to their public release. The Clinton campaign made much of the fact that the State Department information-technology experts found no evidence that any emails had been hacked into, by foreign actors or others. Hence, they argued, even if her keeping work-related emails on her private server was unorthodox, there was no harm.

Also, Bryan Pagliano, a former worker in Clinton’s 2008 presidential campaign whom she then hired at the State Department and who set up her private server, last week was granted immunity in the FBI probe of the email system. He had earlier taken the Fifth Amendment to avoid answering Congress’ questions; now he will have to respond to the FBI.

At issue is exactly how the system was set up, why, if it was a private account, a State Department employee was assigned to create it and what rules other State Department employees were told to follow in forwarding material to the private account – especially in summarizing and conveying information (without being labeled as top secret) that had been so classified when conveyed through the State Department’s official email.

Sen. Bernie Sanders has famously announced that he’s heard “enough, already” about the emails. In another context, Clinton has said, “What difference does it make?” That also sums up the public’s reaction to these recent developments. The minutiae of federal data storage law interest few; the public’s attention has been blunted, and more fundamental questions have gone unanswered.

The most important of these is why Clinton set up a private server in her home. She says she used a private email account for her own convenience – but why the private server? Emails sent through a commercial account, like Gmail, would have been as convenient. Such emails, however, could be retrieved through a lawful court order to Gmail.

By establishing her own server, Clinton was providing for the day when she could wipe that server clean, without worrying about access through a commercial email service provider.

That day came. In December 2014, Hillary Clinton, then a private citizen, sent 30,000 of her emails to the State Department and simultaneously wiped her server clean of all others.

This act might not have been illegal, and for that reason, it has received little attention. What it tells us about Clinton, however, is of tremendous importance to understand the character she would bring to the Oval Office, especially regarding arrogance and lack of candor.

More than a year before Clinton cleaned her server, Congress had subpoenaed documents from the State Department and other federal agencies relative to the attack on the U.S. mission in Benghazi, Libya. At that time, in August 2013, subpoenas were not issued to Secretary of State Clinton herself because the existence of the private server was not known. Congress thought it was looking in all the right places.

When the server became known, Clinton, alone, decided which emails she would send to the State Department for review, and deleted all the rest. That was not her decision to make.

In normal civil litigation practice, when documents are sought for a trial, the parties must issue “litigation holds” to preserve all documents likely to be asked for, well before they are actually demanded and, in some cases, even before a lawsuit is filed. Failure to preserve such documents results in sanctions by the court.

If parties want to withhold documents, they still preserve them, so that the court can eventually make a decision about whether they have to be produced. As a former corporate attorney, Clinton must have known those rules. Her action prevented a neutral third party from ever learning what the emails she erased contained. She was, effectively, acting as the judge in her own case.

Lost in the detail of how the server was set up and messages classified is this fundamental, and undisputed point: Hillary Clinton destroyed possible evidence, on her judgment alone. Richard Nixon might have served out his presidency if he had burned the Watergate tapes. Instead, he held them, argued he did not have to turn them over, and lost. Hillary Clinton was a staff attorney on the Watergate Committee, and she has learned from that experience. Effectively, she has burned the tapes.

Tom Campbell is a professor at the Fowler School of Law at Chapman University. He served five terms in Congress, including on the Judiciary Committee. He has been a law professor for more than 30 years. These views are his own.