Retired Maj. Gen. Walt Huffman, a Texas Tech University law professor who served as the Army's top lawyer, said he would have predicted a year to 18 months behind bars.
"But his career is being terminated. That much is for sure. He's being fired for all practical purposes," Huffman said.
Greg Jacob of the Service Women's Action Network said the case demonstrates the need for legislation that would strip commanders of the authority to prosecute cases and give that power to seasoned military lawyers. The bill, backed by Sen. Kirsten, D-N.Y., was defeated in the Senate earlier this month.
Gillibrand is expected to renew her effort to change military law this spring.
"This case has illustrated a military justice system in dire need of independence from the chain of command," she said in a statement.
A spokeswoman for Sen. Claire McCaskill, D-Mo., who fought the bill, said the case reinforced her side of the argument.
"One of its lessons highlights what we already know — that commanders are often more aggressive than prosecutors in pursuing prosecutions and vetting these cases," Sarah Feldman said.
In another high-profile case Thursday, a military judge in Washington found former Naval Academy football player Joshua Tate not guilty of sexual assault. Three midshipmen were originally charged, but only one was court-martialed.
Prosecutors said the alleged victim was too drunk to consent to sex, and she testified she didn't remember much about that night.
Biesecker reported from Raleigh, N.C. Associated Press writer Donna Cassata in Washington contributed to this report.