Five years into his jail sentence for corruption, former Illinois governor Rod Blagojevich is down to his last appeal, now at the U.S. Supreme Court. His lawyers argue that improper jury instructions resulted in an unfair trial. They raise a vitally important First Amendment point.

Although Blagojevich is an unsympathetic petitioner, the court should hear his case. The disputed jury instructions pose risks to honest politicians and ordinary people who get active in election campaigns. In a world where politically-motivated prosecutions happen too often, a pro-free speech ruling would help cut these risks

So how did we get to this point? It’s because federal courts around the country are interpreting two Supreme Court decisions differently. In some areas, courts hearing corruption cases treat a campaign contribution like a gift to a lawmaker of a winter trip to a Florida beach. That’s both absurd and dangerous to free speech.

In the first of these two cases, the Supreme Court said that to find guilt for extorting a campaign contribution, the law requires “an explicit promise or undertaking by the official to perform or not to perform an official act.” But a year later another Supreme Court ruling in another corruption case created confusion.

Some courts read the second decision as watering down the “explicit promise” requirement. These courts, including the one that hosted the Blagojevich trial, allow conviction under a looser standard. A jury can convict if it infers an implied promise from the candidate’s awareness that the donor expects something in return for a campaign contribution.

This is a dangerous standard. Imagine a retired schoolteacher and her friends attend a rally hosted by an incumbent candidate. They are single-issue voters on Medicare. Afterward, the retiree tells the candidate, “We’re considering donating to your campaign, but we need to know more about your platform. What will you do to protect Medicare?”

The candidate assures them that as long as he is in office, he would vote down any measure that threatens their Medicare. The candidate also says that he needs support from them to win reelection. Satisfied, and believing a campaign contribution could help keep Medicare safe, the retiree and five friends each mail the campaign a $50 check the next day.

Few would consider the contributions by the retirees grounds to charge the candidate for a crime. Yet, under the standard used in the jury instructions in the Blagojevich trial, that is precisely what could happen. The retirees may also be at legal risk. Even if you beat the rap, the legal costs would be ruinous.

These conflicting rulings around the country have created uncertainty for those who contribute to political causes. The Supreme Court finally has a chance to provide clarity and a uniform standard nationally by taking this case. If Blagojevich wins the appeal, the high court would not be ruling on his innocence or guilt. But he would be entitled to a new trial.

Fortunately, there is a common sense way to resolve the differing interpretations and most courts use it now. When Supreme Court Justice Sonia Sotomayor was a Second Circuit appeals court judge, she explained how to resolve the high court rulings. Proof of an express promise isn’t necessary when the payment goes in the pocket of the official, such as cash or a gift.

But if a campaign contribution is made, the First Amendment demands a higher standard of an explicit promise. That’s common sense, but the judge in the Blagojevich trial failed to give the jury such instructions. Using a lower standard for criminal prosecutions for campaign contributions would deter many from donating or running for office. It would enable more politically-motivated criminal prosecutions that interfere with election campaigns.

In 2014, the Supreme Court said that the “First Amendment safeguards an individual’s right to participate in the public debate through political expression and political association. When an individual contributes money to a candidate, he exercises both of those rights.”

In that context, it makes sense to provide additional protections for campaign contributions. Not distinguishing the two gives politically-motivated prosecutors too much leeway, and could subject even small donors to criminal liability. No doubt following such an approach will lead to some abuses. But the opposite is worse.

To paraphrase the court in another case, a criminal law can’t be construed with the assumption that the government will wield its power responsibly. In Blagojevich’s case, the Supreme Court has a chance to reinforce the free speech rights of all Americans, rich and poor alike. It should take it.

This post originally ran in The Hill on April  10th 2018.