Prosecutors and defense lawyers were back in federal court this week working out the schedule for the trial of former U.S. Senator and presidential candidate John Edwards.

Everyone on both sides stipulates that Edwards is a sleaze. But the case against him is so weak that almost no legal experts outside of the Justice Department think he deserves conviction.

So why a trial and the threat of jail time for a single parent raising two young children?

For all the publicity about Edwards’s tawdry conduct, there’s a little-noticed back story to this case that answers that question -- and helps illuminate how poisonous and ridiculous American politics has become.

The facts of the case aren’t in dispute. Edwards allegedly solicited more than $900,000 from two wealthy friends to house and hush-up his mistress, Rielle Hunter. (Edwards is independently wealthy but couldn’t spend his own money on Hunter without his wife, Elizabeth Edwards, finding out.)

Because campaign-finance law allowed donations of no more than $2,300 per person in the 2008 presidential primary, the government claims the gifts from supporters Fred Baron (now deceased) and Rachel “Bunny” Mellon (a 100-year-old heiress) were illegal.

Prosecutors argue that, even though the money didn’t go toward normal campaign expenses such as TV ads and phone banks, the gifts constituted campaign contributions because they were used in “an effort to protect and advance his candidacy from disclosure of an ongoing extramarital affair and the resulting pregnancy.”

No Intent

But there’s no evidence of an intent to skirt the $2,300 limit, as campaign-finance law would require. Edwards wasn’t hiding the gifts to avoid violating arcane campaign rules; he was hiding them to avoid looking like a skunk.

Scott E. Thomas, the former chairman of the Federal Election Commission, insists that the Edwards case is not only not a criminal matter, but it isn’t even a civil violation of campaign-finance law. Thomas said he believes that the lone FEC precedent cited by the prosecution “does not support the government’s novel and misguided theory.”

Intent to avoid embarrassment is an almost-comical legal standard, but there’s nothing funny about the possible precedents being set here. If Edwards loses, it would mean that any friend or relative who provides any personal gifts to any candidate might be subjecting that candidate to criminal prosecution.

Your son has given up his job to run for Congress, so you pay your grandson’s college tuition? That could look like a backdoor campaign contribution to the feds and suddenly Sonny Boy is headed for the slammer.

Criminalized Friendship

Talk about perverse. The same legal system that is prosecuting Edwards for taking money from supporters to shield himself from personal embarrassment permits special interests seeking legislative favors to shower members of Congress with contributions. We’ve criminalized friendship and legalized bribery.

The whole idea of prison for Edwards is bizarre. Even in the most serious FEC cases, the penalty is almost always a fine or slap on the wrist. When I asked Justice Department officials for an example of a politician who went to jail for violating federal campaign-finance laws, they couldn’t come up with one.

So why is this case being brought?

Payback

The explanation begins 20 years ago, when Senate Democrats blocked the nomination of Judge Terrence Boyle to the U.S. Court of Appeals for the 4th Circuit, which includes North Carolina. As payback for impeding his man, then-Senator Jesse Helms blocked all of the North Carolina judicial nominations of Edwards and President Bill Clinton for eight years. After George W. Bush became president, the wheel turned again and Edwards stymied Republican judges, including Boyle when he was re-nominated.

One of the main Republicans opposing Edwards in this bitter struggle over judges was George Holding, who worked for both Boyle and Helms (and who donated to Edwards’s opponent during his 1998 Senate campaign).

Holding became the U.S. attorney in eastern North Carolina in 2006. It shouldn’t surprise you that he was the one who first brought the case against Edwards.

Conflicts of Interest

Despite this obvious conflict of interest, Holding declined to recuse himself. Instead, he spent almost two years trying to determine whether the money from Baron and Mellon went into campaign coffers. When he failed to find that, he hatched a new legal theory that it didn’t matter -- because the money should have gone into the campaign.

After President Barack Obama took office, the state’s senior senator, Richard Burr, wanted Holding to stay on as U.S. attorney in part to finish the Edwards investigation. Burr said that Obama’s proposed replacement, Thomas Walker, would have a conflict of interest in the case because he had donated to Edwards’s campaign. Funny, Burr didn’t have a problem with Holding contributing to Edwards’s opponent. I’m shocked.

Spineless Democrats complied. North Carolina’s other senator, Democrat Kay Hagan, felt she had to prove how much she disapproved of Edwards and has gone along with Holding (who will leave his post in July) and Burr.

The same goes for the Obama Justice Department, which is now running the Edwards prosecution. Attorney General Eric Holder is letting the head of the criminal division (and his former law partner), Lanny A. Breuer, handle the case.

Internal Politics

It may look less political that way, but it’s just another kind of politics -- internal Justice Department politics. Once the case left North Carolina, it became about bolstering the reputations of prosecutors who like to put notches on their belts.

Breuer and Jack Smith, of the department’s public integrity section, need a win. In recent years the department has failed to bring cases against former Representative Tom DeLay and former Senator John Ensign and blown the case against the late Senator Ted Stevens.

I learned recently that during pretrial plea talks in the Edwards case, Breuer, determined to make an example, offered a strange deal: If Edwards pleaded guilty to a felony (which would wreck almost anything he hopes to do with the rest of his life), he could avoid jail time. If he pleaded to a misdemeanor, which he was inclined to do, he would have to serve six months.

After Elizabeth Edwards died in December, he became the sole parent of Emma Claire, 13, and Jack, 11. He refused the deal and will take his chances at trial.

It’s hard to shed tears for John Edwards. And plenty of people serve time in jail when their families need them. But at a time when the Supreme Court has allowed unlimited corporate money to legally flow into political races, bringing this case shows colossal misjudgment.

(Jonathan Alter is a Bloomberg View columnist. The opinions expressed are his own.)

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To contact the writer of this column: Jonathan Alter at alterjonathan@gmail.com.

To contact the editor responsible for this column: Timothy Lavin at tlavin1@bloomberg.net.