Julissa Reynoso, U.S. deputy assistant secretary of state for Western Hemisphere affairs, said the United States was following the case closely. "We hope that Alan Gross is released," she said.
Gross' Cuban attorney, Nuris Pinero, arrived at the Supreme Court on Friday morning to present oral arguments. She and other participants emerged less than two hours later after the hearing apparently concluded.
Gross, wearing a dark suit, was seen from a distance exiting the courthouse guarded by state security agents and getting into a brown car. Representatives of the U.S. Interests Section, which Washington maintains in Havana in the absence of an embassy, were also present. Journalists were not allowed inside.
Cuban authorities said in a message published in official media that Gross had exercised his right to address the court and had thanked the judges for the opportunity to explain his case personally.
The court will rule "in the coming days," the statement read.
Gross' U.S. attorney, Peter J. Kahn, said that during the hearing, "Alan reiterated that he never had any intention of hurting the Cuban government or its people, and that he has always believed - and still does so today - in the sovereignty of the Cuban nation and its people."
Kahn said Gross' conviction and sentence were "not warranted by either the law or the facts of his case."
While U.S. officials have said they do not anticipate Gross' conviction being overturned outright, there is hope that the end of the legal process might clear the way for his release on humanitarian grounds. Gross has lost 100 pounds in prison, and several of his family members are seriously ill.
Cuban officials have said privately that they are sympathetic to humanitarian appeals but would not consider them until Cuba's Supreme Court weighs in.
Gross' arrest sparked debate in Washington over the efficacy of the democracy programs, which are passionately supported by several Cuban American politicians. In April, Senate Foreign Relations Committee Chairman John Kerry put a hold on funding, arguing that the programs don't work and have in fact harmed U.S. interests.