FORT MEADE, Md.—A military judge on Tuesday rejected the Obama administration's quest to equate the unlawful disclosure of documents with aid to America's mortal enemies, including al Qaeda, in a ruling that acquitted Private First Class Bradley Manning of the gravest criminal charge he faced.

But Pfc. Manning was convicted of a long list of other crimes, including theft of government property and violations of the Espionage Act, and faces a potential prison sentence far longer than any yet given for leak-related crimes.

The outcome of the high-profile case, coming more than three years after Pfc. Manning was arrested at a military base in Iraq for leaking thousands of secret documents and videos to the WikiLeaks website, was decidedly mixed for both the defendant and his prosecutors.

It showed that prosecutors had a strong case against Pfc. Manning for taking and leaking government secrets, experts said, but that the government may have overreached by taking the added step of attributing his actions to an intent to harm the U.S. by aiding its enemies.

"The judge reined in a clearly overzealous prosecution," said Mary Rose Papandrea, a Boston College Law professor.