U.S. Supreme Court justices seemed skeptical during appeal arguments last week regarding the corruption conviction of former Gov. Bob McDonnell.

Left-leaning Justice Stephen G. Breyer said that the federal corruption laws under which McDonnell was convicted “puts at risk behavior that is common.” Right-leaning Chief Justice John G. Roberts Jr. raised similar points.

At issue is the Hobbes Act, which makes honest-services fraud illegal. In some interpretations of that law, a clear quid pro quo isn’t needed — meaning a public official doesn’t have to perform a specific beneficial act in exchange for money or services to get in trouble.

McDonnell, whose conviction on 11 corruption charges was upheld by the U.S. 4th Circuit Court of Appeals, contends that he performed no specific act that clearly benefited vitamin supplement salesman Jonnie R. Williams Sr.

Prosecutors showed how Williams gave McDonnell, his wife, Maureen, and their family more than $177,000 in cash, loans and gifts, including a Rolex watch.

McDonnell’s lawyers argue that he did nothing more than any politician would do and that federal prosecutors exercised too much power when they went after him.

The judges appeared to be siding with McDonnell last week, but it’s too early to tell, say law professors Jeffrey Bellin, of the College of William and Mary Law School, and Henry L. Chambers Jr., of the University of Richmond Law School.

“I think the justices may find the case harder than they think when they sit down to write the opinion, though,” Bellin says, “so we will have to wait and see how the court ultimately rules.”

The Supreme Court is an unusual position because of conservative Justice Antonin Scalia’s recent death. With no one chosen as his replacement, the court is evenly matched with liberals and conservatives.

The professors say that if the justices vote 4-4 on the appeal, McDonnell’s convictions stand and he’ll likely go to prison to serve all or part of his two-year sentence.

If the court finds the Hobbes Act to be unconstitutional, then McDonnell wins his appeal, they say.

And if the court finds that U.S. District Judge James Spencer, who presided over McDonnell’s six-week-long trial in 2014, was too broad in his instructions to the jury, then McDonnell will go free but could be tried again. His wife’s appeal has been put on hold for now.

McDonnell’s appeal has drawn national interest because its outcome could have an important impact on public corruption cases throughout the United States.

In other high-profile cases, former Illinois Gov. Rod Blagojevich and former Alabama Gov. Ron Siegelman were convicted of federal corruption laws.

But those cases aren’t similar to McDonnell’s, Chambers says, “and no one is going backward” — meaning that if McDonnell is acquitted on constitutional grounds, the other cases would be unaffected.

The Supreme Court is expected to rule by late June. And whatever its decision, future corruption cases will be affected.

If the convictions are reversed, prosecutors will have a more difficult time going after politicians they suspect of corruption. And if the justices affirm the conviction, Bellin says, “It would send a strong signal to politicians across the country to be careful about doing favors for big donors.”