When I was hired as a prosecutor for the Department of Justice, I was told repeatedly that my job was to do justice, not just put people behind bars. With that in mind, where is the justice in the department’s prosecution of Doug Hampton, once a top aide to disgraced former Sen. John Ensign (R-Nev.), while at the same time ignoring the criminal conduct of the Senator? Hampton has been charged with — and has admitted in numerous interviews with reporters — violations of the laws limiting lobbying by former staffers for a year after their departure from the Senate.

Why did Hampton willfully violate the lobbying restrictions? Because he had been fired from his position — not because of any job performance issues, but so Ensign could more easily pursue his affair with Hampton’s wife. Hampton was suddenly left without a job to support his family and three children.

Rather than ending the affair as his spiritual adviser Tim Coe and friend Sen. Tom Coburn (R-Okla.) implored him to do, Ensign carried on, even though — as the report of the Senate Ethics Committee special counsel indicates — the object of his affections, Cindy Hampton, wanted to end it. It was not much longer before Cindy Hampton also lost her job as treasurer of the Senator’s campaign committee. Notably, Ensign’s wife called to fire her.

It was Ensign who came up with the idea for Hampton to become a lobbyist. Ensign arranged a consulting firm position for Hampton, found clients for Hampton and then met with those clients on Hampton’s behalf.

The Ethics Committee special counsel identified at least 30 instances in which Hampton contacted a Senate official but noted it was likely there were others. Although Hampton mostly lobbied Ensign’s office, Coburn once admitted to the New York Times that, knowing it was wrong, he had allowed Hampton to lobby him as well.

The Ethics Committee obtained immunity from prosecution for an unknown number of witnesses, including Ensign’s chief of staff, John Lopez, Hampton’s contact in the Senator’s office. Further, despite initial bellicose assertions of confidentiality, Coburn cooperated extensively with the committee, suggesting he too may have received immunity.

The committee’s request for immunity for Hampton, however, was denied. Finally, in March, Hampton was indicted, but the Justice Department indicated it was not pursuing the case against Ensign. The department had decided to prosecute a victim — certainly not an entirely innocent victim, but nonetheless, a victim — of a powerful politician’s obscenely self-centered desires. In his eagerness to tell the world about Ensign’s transgressions, Hampton confessed to criminal conduct, making it hard for the Justice Department to ignore. But Hampton’s repeated public statements also inculpated Ensign in wrongdoing. In addition, the contemporaneous notes that Hampton took suggested the Senator had committed the additional felony offense of failing to report the $96,000 severance payment to the Federal Election Commission as the law requires. Why is it the Ethics Committee could figure this out, but the Department of Justice could not?

Hampton’s indictment would have seemed harsh but at least fair had Ensign, his clear — and more culpable — co-conspirator, been indicted at the same time. By taking a hard line against Hampton but going easy on Ensign, it looks like the Department of Justice is protecting the rich and powerful at the expense of the poor and powerless. Hardly the sort of justice that supervisors at the U.S. Attorney’s Office taught us to aim for.

Prosecuting Hampton, but not Ensign, is not justice at all.

Melanie Sloan is executive director of Citizens for Responsibility and Ethics in Washington.