Private Manning, 25, is accused of the largest leak of classified information in United States history, and there is no public record that a military court has ever heard a case involving the aiding-the-enemy charge. His trial has illustrated the extent to which the Obama administration has cracked down on people accused of leaking documents or other information to news organizations, in both military and civilian courts.

Private Manning is one of a record seven current or former government employees charged with violating the Espionage Act by leaking classified information since President Obama took office. In a report last month, the Congressional Research Service said the cases “demonstrate the Obama administration’s relatively hard-line policy” on unauthorized disclosures.

At least two people have been charged in civilian courts with violating another secrecy law, the Intelligence Identities Protection Act, which is intended to prevent federal agents’ names from being released.

During a court hearing in February, Private Manning conceded that he possessed and handed over, among other things, diplomatic cables, parts of the Iraq and Afghanistan war logs, files on detainees at Guantánamo Bay, two intelligence memos and a video of an Apache helicopter attack in Iraq that killed two Reuters journalists.

“I found the video troubling at the time, your honor, and I still do, but it’s just my opinion, though,” he said at the time. “As I hoped, others were just as troubled — if not more troubled.”

Steven Aftergood, the director of the Project on Government Secrecy at the Federation of American Scientists, said in an interview on Tuesday that “the video arguably was a matter of overriding public interest.”

“But many other records released by Manning and WikiLeaks had no obvious news value or larger public interest,” he added. “Manning had privileged access to restricted information. Not only did those records expose individuals to potential retaliation, but their publication signaled that the U.S. could not guarantee confidentially to others.”

Ben Wizner, of the American Civil Liberties Union, said that was beside the point.

“It doesn’t matter if it’s a classified document or a Kleenex,” Mr. Wizner said. “The aiding-the-enemy statute does not require the information divulged be classified.”