WASHINGTON — The Supreme Court on Wednesday seemed ready to side with Bob McDonnell, the former governor of Virginia who was convicted of public corruption and faces two years in prison. Justices across the ideological spectrum said the laws under which he had been convicted gave prosecutors too much power to convert routine political favors into forbidden corruption.
"It puts at risk behavior that is common," said Justice Stephen G. Breyer. "That is a recipe for giving the Justice Department and prosecutors enormous power over elected officials."
McDonnell, a Republican, was prosecuted on charges that he had used his office to help a businessman, Jonnie R. Williams Sr., who had showered the governor and his wife with luxury products, loans and vacations worth more than $175,000. The gifts themselves were legal, and the question in the case was whether they were part of a corrupt bargain in which McDonnell reciprocated by using the power of his office to help Williams.
McDonnell, who attended Wednesday's argument, arranged meetings for and attended events with his benefactor. But Williams, whose company made a diet supplement, met with no real success in obtaining support for his product from the state. A jury found that McDonnell's actions amounted to corruption, and a federal appeals court upheld the conviction.
Noel J. Francisco, a lawyer for McDonnell, said his client should not have been convicted as he did not "make a government decision or urge someone else to do so." The corruption laws, he added, were "not meant to be comprehensive codes of ethical conduct."
Michael R. Dreeben, a lawyer for the federal government, said that such a narrow definition was "a recipe for corruption" that would "send a terrible message to citizens."
Breyer responded that the court was not in the business of sending messages. Justice Anthony M. Kennedy added that "the government has given us no workable standard" to distinguish political favors from criminal acts.
Last year, the Supreme Court allowed McDonnell to stay out of prison while the court considered whether to hear his case, McDonnell v. United States, No. 15-474. That unusual order was a powerful hint that the court might be inclined to rule in his favor.
But McDonnell lost a probable ally in February, when Justice Antonin Scalia died. Scalia was the court's most prominent proponent of limiting the scope of federal anti-corruptions laws, saying of one that it had been "invoked to impose criminal penalties upon a staggeringly broad swath of behavior."
In urging the Supreme Court to hear his appeal, McDonnell's lawyers said he had done no more than extend "routine political courtesies" to Williams.
"This case marks the first time in our history that a public official has been convicted of corruption despite never agreeing to put a thumb on the scales of any government decision," McDonnell's lawyers said in a second brief. "Officials routinely arrange meetings for donors, take their calls, politely listen to their ideas, and refer them to aides."
"In criminalizing those everyday acts," the brief said, "the government has put every federal, state, and local official nationwide in its prosecutorial cross hairs."
The brief noted that in the Citizens United decision in 2010, the Supreme Court said that "ingratiation and access" are "not corruption." That same year, the court ruled in favor of a former Enron executive, Jeffrey K. Skilling, saying that a federal anti-corruption law governing "honest services" applied only to bribes and kickbacks.
In urging the Supreme Court not to hear the case, Solicitor General Donald B. Verrilli Jr. said the prosecution of McDonnell had been unexceptional.
"A public official violates federal corruption statutes where, as here, he accepts personal benefits in exchange for his agreement to influence government matters," Verrilli wrote, adding that "the failure of a bribery scheme does not make it lawful."
On Wednesday, Breyer said McDonnell's case presented "as knotty and complicated and difficult a problem as I can think of."