Nearly 300 professors and legal scholars from around the nation have signed an open letter calling on the government to end the detention of Bradley Manning, the soldier charged with passing classified information — including more than 250,000 U.S. diplomatic cables — to WikiLeaks.

Written by Yale law school professor Bruce Ackerman and Harvard law school professor Yochai Benkler, the letter argues that Manning is being detained under “degrading and inhumane conditions” that violate the U.S. constitution. It appears in the most recent issue of the New York Review of Books and was also published online in March, where it attracted 295 signatories.

The letter alleges that the treatment of Manning, which includes keeping him in solitary confinement for 23 hours a day and requiring him to strip naked except for a “smock,” is illegal under the Eighth Amendment, which prohibits cruel and unusual punishment, and the Fifth Amendment, which prohibits punishment without trial.

The authors write:

If Manning is guilty of a crime, let him be tried, convicted, and punished according to law. But his treatment must be consistent with the Constitution and the Bill of Rights. There is no excuse for his degrading and inhumane pre-trial punishment. As the State Department’s PJ Crowly put it recently, they are “counterproductive and stupid.”

They also appeal to President Obama, as a former professor of constitutional law himself, to uphold “fundamental standards of decency.”

In an e-mail to the News, Ackerman said he wrote the letter because he considers Manning’s situation a “test case” of how the Obama administration will act in the future.

“I’ve been generally concerned with the extent to which the Obama administration is in fact making a significant break from the manifold illegalities of the so-called ‘war on terror’ of the Bush era,” he said.

Manning has been held at the Quantico marine base in Virginia since July 2010, where he awaits a court-martial, The Guardian reported.